Last Saturday, we drove to Lake Quannapowitt in Wakefield for a bit of longboard racing at the Quannapowitt Yacht Club to get a bit of practice before the WET Fall Regatta and the Ocean Air Windfest in October. This is a small but very lovely venue. 16 windsurfers participated, most of them on longboards from the 1980s and 1990s. This was probably the largest number of F2 Lightning Race boards at one location in the US for the year!
For Nina and me, this was a big learning experience. We always sail at locations with very steady wind- mostly the ocean, or large bays like Hatteras or the Laguna Madre near Corpus Christi. At the little inland lake, the wind was a lot gustier - the local wind meter showed readings between 0 and 25 mph during the time of the races! We both briefly considered giving up and not racing at all, after sudden lulls and direction changes had dropped us into the water what seemed like 10 times in the first 5 minutes. In the first race, Nina came in dead last. I probably would have taken that spot, but my uphaul broke on the way out, and I missed the race completely while replacing the uphaul.
In the second race, I think I was successful in stealing the last place from Nina. I held back at the start since I did not want to be in everyones way after falling right before the start line, which seemed very likely. A lot of the racers have been racing continuously for the 36 years that this September race has been held, and I think the first one finished the race while I was just rounding the first mark. But at least, my falls were getting a bit less frequent. We did about 4 races around 4 buoys, and then one long race around the entire lake, before breaking for lunch, and another 4 races in the afternoon. By the last race, my arms were starting to cramp up from holding the 8.5 - with the gusty winds, hooking in was a luxury that was limited to only short periods in some races.
The cool thing about so many races in one day was that we got lots of starting practice, which I sorely needed. I discovered a whole bunch of ways to screw up the start, but in the last races, I managed to get across the starting line in the first third of the field. Somehow, I also ended up in a similar position at the finish line a few times, and in the top half of the overall rankings. After the early falls, my goal had been to simply not finish last in all races - goal accomplished!
It was a ton of fun to race with a mixed crowd of enthusiastic longboard racers - some who were struggling as much as I was at the beginning, but also several others who where way better racers than I am. The organization was perfect, and so was the weather. What a great day!
Below is a video from my helmet cam from on of the afternoon races, and GPS tracks from the same race.
Monday, September 30, 2019
Sunday, September 22, 2019
Tracks for the Skate
After discovering that simply replacing a powerbox with a foilbox did not work well for my Skate 110 and Slingshot Inifity 84 foil, I decided to put a couple of US fin boxes in the board so that I could use the pedestal mount for the foil. The big advantage of the track mount is that it gives a few inches of room for adjustments so the foil can be place at just the right spot. Here's a picture of the finished installation:
We got a bit of wind today, so I took the combo out for a test run with the i84 foil, the 71 cm mast, and my 6.5 m Gaastra Matrix sail. The session was a bit frustrating because the chop was quite high even though the wind was light - too light to waterstart most of the time. I also had to get used to the foot straps on the board (I don't use any on the 71 cm wide slalom board I usually foil on), and had a hard time with tacking - after sailing a lot on the wider slalom board, I often stepped too far to the outside or even next to the board. Bad turns and uphauling in chop - not my favorite combo!
But the good news was that moving the foil forward worked as expected, and so did the track mount. I had the mast in "C" position on the fuselage, and pushed the pedestal all the way to the back. Here's a video from one of the longer runs:
I had put a Slingshot half footstrap in the back, since installing the foil box had removed the rear screw holes in the center. It actually was too far back for the foil position, so I ended up not using it. I'll either turn it around and mount it as far back as possible, and/or I'll have to mount the foil in "B" position on the fuselage. That would move it a couple of inches further back, but the track mount makes it easy to fine tune the position.
There were plenty of crashes in this session. Here's one where it looks like I'm going for a Gecko:
That would be a rather questionable idea without using the rear strap .. and with the foil behind me to fall onto! Maybe all the water that seems to be coming out of my head in the next picture can be blamed :-).
We got a bit of wind today, so I took the combo out for a test run with the i84 foil, the 71 cm mast, and my 6.5 m Gaastra Matrix sail. The session was a bit frustrating because the chop was quite high even though the wind was light - too light to waterstart most of the time. I also had to get used to the foot straps on the board (I don't use any on the 71 cm wide slalom board I usually foil on), and had a hard time with tacking - after sailing a lot on the wider slalom board, I often stepped too far to the outside or even next to the board. Bad turns and uphauling in chop - not my favorite combo!
But the good news was that moving the foil forward worked as expected, and so did the track mount. I had the mast in "C" position on the fuselage, and pushed the pedestal all the way to the back. Here's a video from one of the longer runs:
I had put a Slingshot half footstrap in the back, since installing the foil box had removed the rear screw holes in the center. It actually was too far back for the foil position, so I ended up not using it. I'll either turn it around and mount it as far back as possible, and/or I'll have to mount the foil in "B" position on the fuselage. That would move it a couple of inches further back, but the track mount makes it easy to fine tune the position.
There were plenty of crashes in this session. Here's one where it looks like I'm going for a Gecko:
That would be a rather questionable idea without using the rear strap .. and with the foil behind me to fall onto! Maybe all the water that seems to be coming out of my head in the next picture can be blamed :-).
Monday, September 16, 2019
Rules and Accidents
Windsurfing accidents happen. All windsurfers loose control from time to time, and on a crowded day, this can lead to people crashing into each other. Most of the time, it's no big deal. The windsurfer who messed up knows it, apologizes, and (hopefully) offers to pay for any damages.
But every now and then, the outcome is different. This post analyzes one such incident that happened at the beginning of August at Kalmus. We will look at the accident based on statements the two involved windsurfers made; an eye witness report; and GPS tracks from one of the windsurfers that show exactly where the accident happened. The accident will be analyzed using the "U.S. Inland Navigation Rules" and the "International Regulations for Preventing Collisions at Sea" (Colregs), which govern all boating traffic in the US, as they are described on the US Coast Guard website.
Sailor 2 ("GG") also likes to sail fast, but can most often be seen on raceboards. He is a regular participant at the raceboard world and national championships, and has won races several times at the East Coast Windsurfing Festival Cape Cod. In the past, he had trained with the Spanish olympic team, and trained the olympic youth division in Spain. GG is a professor at Harvard.
The eye witness ("PF") is a regular sailor at Kalmus who happened to be at the beach at the time of the incident.
The analyst - that's me. I have been windsurfing for 40 years. I originally learned windsurfing at the University of Konstanz in Germany. The 3-day course included a final written exam where knowledge of the "right-of-way rules" was required to earn the "VDWS Grundschein", a certificate needed to rent windsurfing equipment. I am a US Sailing certified Windsurfing Instructor, and Instructor Trainer/Examiner with the Windsurfer Instructor and Programs Association (WIPA). I have participated in a number of windsurfing races, including the 2018 US Windsurfing Nationals, and organized the East Coast Windsurfing Festival Cape Cod for a number of years, where I also had the race director role.
This description matches how GG described the accident. GG added that he was planning to go in after this run.
CM added that he had to jibe because of the stones in the water, and that he believed that he had the right of way because GG was on port.
The damage went from the top to the bottom of the board, went through both the laminate and the sandwich layer, and included breaking the styrofoam core. Cape Cod Windsurfing offered to repair the board for $150. The board was in excellent shape before the accident, and even a professional repair would lower the resale value of the board by several hundred dollars.
Zooming in on the last run and the accident shows that the accident happened close to shore:
The yellow line in the image above is 100 feet long. Typical jibe diameters are between 150 and 200 feet, so it is clear that GG did not have sufficient room to jibe. This confirms his statement that he was on his planned last run of the day. The first GPS picture shows that he was planning to exit the water at the same place where he had launched and exited before. He was in the process of slowing down to stop, and his speed had dropped from 23 knots to about 18 knots when CM hit him.
But every now and then, the outcome is different. This post analyzes one such incident that happened at the beginning of August at Kalmus. We will look at the accident based on statements the two involved windsurfers made; an eye witness report; and GPS tracks from one of the windsurfers that show exactly where the accident happened. The accident will be analyzed using the "U.S. Inland Navigation Rules" and the "International Regulations for Preventing Collisions at Sea" (Colregs), which govern all boating traffic in the US, as they are described on the US Coast Guard website.
The Parties
Sailor 1 ("CM") has been a regular windsurfer at Kalmus for more than 2 decades. He loves to sail fast, and used only slalom gear until last year, when he switched to fast freeride gear. CM is the singer in a wedding band.Sailor 2 ("GG") also likes to sail fast, but can most often be seen on raceboards. He is a regular participant at the raceboard world and national championships, and has won races several times at the East Coast Windsurfing Festival Cape Cod. In the past, he had trained with the Spanish olympic team, and trained the olympic youth division in Spain. GG is a professor at Harvard.
The eye witness ("PF") is a regular sailor at Kalmus who happened to be at the beach at the time of the incident.
The analyst - that's me. I have been windsurfing for 40 years. I originally learned windsurfing at the University of Konstanz in Germany. The 3-day course included a final written exam where knowledge of the "right-of-way rules" was required to earn the "VDWS Grundschein", a certificate needed to rent windsurfing equipment. I am a US Sailing certified Windsurfing Instructor, and Instructor Trainer/Examiner with the Windsurfer Instructor and Programs Association (WIPA). I have participated in a number of windsurfing races, including the 2018 US Windsurfing Nationals, and organized the East Coast Windsurfing Festival Cape Cod for a number of years, where I also had the race director role.
The Context
The accident happened at Kalmus on August 3, 2019 at 6:23 pm. Wind was from the SSW-SW at 20 mph, gusting to 25. Most windsurfers had stopped sailing by then, and were in the parking lot packing their gear or had left already. Earlier in the day, the parking lot had been completely full, and the beach packed, due to a soccer tournament.The Accident
According to the eye witness, both windsurfers were sailing almost parallel to the beach towards the launch area. GG sailed downwind, CM sailed upwind. CM jibed at the last possible moment before the stone sea wall on the west end of the beach, and crashed into GG.This description matches how GG described the accident. GG added that he was planning to go in after this run.
CM added that he had to jibe because of the stones in the water, and that he believed that he had the right of way because GG was on port.
After the Accident
GG noticed substantial damage to the board and approached CM, expecting an apology. Rather than getting an apology, he was told by CM in a raised voice that he had done a "dick move" by not jibing when CM expected him to jibe. When GG pointed out that he was the "stand by" boat in the given situation since he was the downwind sailor, CM started a shouting match from which GG walked away. In a second discussion later in the parking lot where GG explained which navigation rules applied in the situation, CM disagreed and suggested that they should "agree to disagree". CM refused to pay for the repair of GG's damaged board.The Damage
GG's windsurf board sustained significant damage in the accident, as shown in the following picture:The damage went from the top to the bottom of the board, went through both the laminate and the sandwich layer, and included breaking the styrofoam core. Cape Cod Windsurfing offered to repair the board for $150. The board was in excellent shape before the accident, and even a professional repair would lower the resale value of the board by several hundred dollars.
GPS Tracks
GG used a GPS to record his windsurfing sessions, and submitted his GPS data for analysis. Here is a picture of his tracks for the day (click on the image to see a larger version):Zooming in on the last run and the accident shows that the accident happened close to shore:
The yellow line in the image above is 100 feet long. Typical jibe diameters are between 150 and 200 feet, so it is clear that GG did not have sufficient room to jibe. This confirms his statement that he was on his planned last run of the day. The first GPS picture shows that he was planning to exit the water at the same place where he had launched and exited before. He was in the process of slowing down to stop, and his speed had dropped from 23 knots to about 18 knots when CM hit him.
Analysis
The two windsurfers involved in the accident propose two different theories about who was at fault.
1. CM states he was on starboard, and GG was on port. The windsurfer on port would be the "give way" vessel and would have to change course to avoid a collision.
2. GG states that CM was upwind before the collision, and therefore the "give way" vessel. Furthermore, CM was in the middle of a jibe, and a sailboat or windsurfer does not have right of way during a maneuver.
A further uncertainty arises from the question whether CM was overtaking GG. CM generally tries to sail as fast as possible, and typically uses larger sails than other windsurfers; the often passes other windsurfers on the water. Since GG was slowing down to stop, it is quite possible that CM passed GG before jibing.
Assuming that CM passed GG before jibing, the rules that apply are defined in rule 13 of the "Amalgamated International & U.S. Inland Navigation Rules": "any vessel overtaking any other shall keep out of the way of the vessel being overtaken." The overtaking boat has the"duty of keeping clear of the overtaken vessel until she is finally past and clear". This means the overtaking windsurfer may not just pass another windsurfer, and then immediately change course or speed to a collision course. The conclusion is:
If CM passed GG on the way in, he did not meet his obligation of "keeping clear", and was at fault at the accident.
Since we cannot know for certain if CM passed GG before jibing, we must also look at the incident assuming that he did not pass him first. Common sense tells us you can't just jibe from an upwind position to get starboard rights just before you crash into someone - the other person would not even have time to react to avoid the collision! But is there something in the rules that we applies?
The first rule that does apply is Rule 6 - "Safe Speed":
"Every vessel shall at all times proceed at a safe speed so that she can take proper and effective action to avoid collision and be stopped within a distance appropriate to the prevailing circumstances and conditions."
If one windsurfer sails in a straight line, and one windsurfer changes course, only the windsurfer changing course can actually know that the collision may happen, so it is his obligation to slow down or stop.
Furthermore, Rule 7 - "Risk of Collision" states:
"Every vessel shall use all available means appropriate to the prevailing circumstances and conditions to determine if risk of collision exists. If there is any doubt such risk shall be deemed to exist."
In clear text: if you jibe and are not sure that you will be clear of anyone else in the area, you must assume that you are creating a risk of collision. Rule 8 covers actions to avoid collision, and Rule 8 e again states:
" If necessary to avoid collision or allow more time to assess the situation, a vessel shall slacken her speed or take all way off by stopping or reversing her means of propulsion."
Other parts of Rule 8 state:
"Action taken to avoid collision with another vessel shall be such as to result in passing at a safe distance " and
"Any action taken to avoid collision shall be taken in accordance with Rules 4-19 and shall if the circumstances of the case admit, be positive, made in ample time and with due regard to the observance of good seamanship"
From the rules above, we can deduct the general guideline that you do not have any right of way when you maneuver. Whenever you jibe or tack, it is 100% your responsibility to make sure you do not crash into someone.
The bottom line is simple: you cannot just jibe into someone! You either have to jibe so you pass them in a safe distance (which is at least a mast length), or do it so that they have "ample time" to see you and adjust their course. If that is not possible, you'll have to stop, if necessary. In a situation like here, of course, the accident could have easily been avoided if the upwind sailor (CM) had tacked instead of jibed.
Why bother?
Some of my readers may wonder why I bother posting about this, especially since the incident happened more than a month ago. I am not naive enough to think that CM will read this post, follow the links to the rules, and then say "Oops, now I understand I was wrong", then apologize to GG and offer to pay for the repair. I would not expect this from someone who forces windsurfing women off their boards rather than showing some courtesy, and then yells at anyone trying to explain to him the right of way rules.
However, a few other windsurfers I talked to stated they were not sure what the rules were in such a situation, and they may find the discussion and links above helpful.
The final straw, though, was CM's continued aggressive behavior. In the past month, he had shown often that he will jibe where and when he wants to, and if someone is in the way, that's their problem. At least once, he has been seen getting dangerously close to another windsurfer. Together with the fact that his jibes have become a lot worse, with much less control and a higher crash rate than in the past, he is a danger to other sailors. Perhaps this was always the case - others tell stories where he almost got beaten up by slalom sailors at Kanaha for jibing too close to their spouses. But with his deteriorating skills and complete lack of consideration for others, he is becoming more dangerous than he was. This particular accident, in the end, had a "lucky" ending, with only a board getting damaged. Just a foot to either side, and a person would have been hit, which likely would have resulted in broken bones.
He also seems more willing to insult and threaten people than perhaps learn from the incident. When he pulled into the Kalmus parking lot a couple of days ago and noticed that I was telling Andy Brandt about the incident, it would have been a great opportunity to check with Andy if his understanding of the situation was correct - who'd know better than Andy? But instead, he rolled up to where I was rigging, and started to insult me and my friends ("you can't sail and everyone you hang out with is a bad sailor" were his kindest words), and yell at me that this was none of my business. Well, he's wrong about that. If I see someone who sails dangerously enough to cause crashes with significant damage to other windsurfer's equipment, without any signs of regret or change, I certainly will not be quiet about it. Approaching me to intimidate and insult me to keep me quiet won't work, either.
Sunday, September 8, 2019
GPS Device Poll - Initial Results
Below are some initial results from the device poll. 86 people answered the questions in less than a day.
Saturday, September 7, 2019
GPS Team Challenge Device Poll
Regular readers of this blog may have discovered that I love the GPS Team Challenge. One of the issues that comes up on a regular basis on the "GPS and Speed talk" forum is the question about which GPS devices are allowed. On one hand, the competition aspect requires high accuracy, which means expensive devices which often have drawback; one the other hand, there is a desire for inclusiveness and making it easier and cheaper for new members to join.
One option that has been discussed is to create a two-tier system where postings from just about any GPS device are allowed, but only postings from approved, highly accurate devices count for the competition, that is the monthly and individual rankings. The "other" speedsurfing site, gps-speedsurfing.com, has a similar system in place for "normal" and "record" postings.
I have create a short poll to see what current and potential GPSTC members think about allowing such "two-tiered" postings. You can fill it out here. Below are screen shots:
Only the first 2 questions are required, the rest is optional. Here's the second section:
One option that has been discussed is to create a two-tier system where postings from just about any GPS device are allowed, but only postings from approved, highly accurate devices count for the competition, that is the monthly and individual rankings. The "other" speedsurfing site, gps-speedsurfing.com, has a similar system in place for "normal" and "record" postings.
I have create a short poll to see what current and potential GPSTC members think about allowing such "two-tiered" postings. You can fill it out here. Below are screen shots:
Only the first 2 questions are required, the rest is optional. Here's the second section:
I'm planning on posting the poll results on this blog and on the Seabreeze forum .. if anyone bothers answering the questions! Here's the full address of the poll: https://docs.google.com/forms/d/e/1FAIpQLSejmAe_8ddsp8qawqZ18h5xpuvzbVRlaM5DI3entYkp4seqJg/viewform
Tuesday, September 3, 2019
Squiggles and Half Straps
Yesterday was supposed to be good for foiling in the afternoon, with wind in the mid-teens. We waited for it. And waited. And waited some more. It was almost 5 pm before the meter readings picked up to 13. 45 minutes later, I was on the water at Kalmus. Nina decided not to join me after hearing about jellyfish on shore (a first for this year), and seeing rain showers coming in.
I had rigged the 6.5, which proved plenty big when the wind picked up to 16 mph averages. Since the tide was high, I was able to use the 90 cm mast, which is easier and more fun than the shorter masts. On the back of my zombie slalom board, I had mounted one of the Slingshot "half" footstraps, with the open end facing forward, to test it.
Here are the GPS tracks from the session:
It was a great session! Due to all the jellyfish talk, I skipped working on jibes and just tacked, with 11 of 14 tacks dry. I also crashed once in the middle of a run. The swell was quite big for the light wind, with some 2-foot rollers coming through from time to time. My Infinity 84 foil is quite sensitive to what happens in the water, and going almost parallel to the waves means that the flight height can change quite a bit going up or down a wave. So after a while, I gave up trying to foil in a straight line, and instead played with the swell. When going down a wave, the foil wanted to go drop down to the water; when going up the back of a wave, it wanted to rise up. Once I figured that out, compensating for it by moving the rig or my weight was a fun little exercise. The long mast definitely helped there! Breaches were virtually non-existent, and touch downs were gentle and brief. Drawing squiggly lines in non-breaking wind swell is so much fun!
I liked the half strap in the back. It is quite easy to slip into it sideways, and having the strap helps to have the foot in the right position, and perhaps a bit more control of the board. On the side without the strap, I found myself looking down a lot to see where exactly my foot was. I guess I'll put the second strap on the other side, but leave the front straps off for now.
I kept the session short since it looked like more rain was coming, and I did not want to make Nina wait too long. But doing a short foil session meant that I never reached the point where my attention starts to wander, and crashes slip in. We ended the day by celebrating the end of the tourist season at the British Beer Company. What a great start of September, my favorite windsurfing month of the year!
I had rigged the 6.5, which proved plenty big when the wind picked up to 16 mph averages. Since the tide was high, I was able to use the 90 cm mast, which is easier and more fun than the shorter masts. On the back of my zombie slalom board, I had mounted one of the Slingshot "half" footstraps, with the open end facing forward, to test it.
Here are the GPS tracks from the session:
It was a great session! Due to all the jellyfish talk, I skipped working on jibes and just tacked, with 11 of 14 tacks dry. I also crashed once in the middle of a run. The swell was quite big for the light wind, with some 2-foot rollers coming through from time to time. My Infinity 84 foil is quite sensitive to what happens in the water, and going almost parallel to the waves means that the flight height can change quite a bit going up or down a wave. So after a while, I gave up trying to foil in a straight line, and instead played with the swell. When going down a wave, the foil wanted to go drop down to the water; when going up the back of a wave, it wanted to rise up. Once I figured that out, compensating for it by moving the rig or my weight was a fun little exercise. The long mast definitely helped there! Breaches were virtually non-existent, and touch downs were gentle and brief. Drawing squiggly lines in non-breaking wind swell is so much fun!
I liked the half strap in the back. It is quite easy to slip into it sideways, and having the strap helps to have the foot in the right position, and perhaps a bit more control of the board. On the side without the strap, I found myself looking down a lot to see where exactly my foot was. I guess I'll put the second strap on the other side, but leave the front straps off for now.
I kept the session short since it looked like more rain was coming, and I did not want to make Nina wait too long. But doing a short foil session meant that I never reached the point where my attention starts to wander, and crashes slip in. We ended the day by celebrating the end of the tourist season at the British Beer Company. What a great start of September, my favorite windsurfing month of the year!
Sunday, September 1, 2019
Foil Setup: Front Wing Placement
Isn't it curious how sometimes things can be easy and confusing at the same time? Setting up equipment for windfoiling can be that way. The general rule is simple: "you want the front wing located as close to the center of your stance as possible", the Slingshot manual says. Sound easy, right? Let's look at a few examples, starting with Nina's foil setup:
I placed the ruler close to the middle of the front wing, where the "center of lift" (COL) is. If you compare it to the position of the foot straps, you can see that it is close to the middle, just a bit towards the back strap.
Now lets look at another setup that does not work nearly as well:
This is my Skate 110 with the Slingshot Infinity 84 front wing. It's shown with a 45 cm mast, but ignore the mast size for the time being. Here's a zoom-in:
You can see that the COL is much closer to the back strap. When I tried this setup (with a 71 cm mast), it was hard to get up on the foil, and felt very unbalanced once up. Nina tried it, too, and came to the same conclusion.
What's the difference? In both setups, the foil is mounted in the "C" position on the fuselage, which put the front wing closest to the front. However, my Infinity 84 wing is significantly larger than Nina's i76. All the extra area was added to the back of the foil, which moved the "center of lift" back by about an inch or two. In addition, Nina is using the Powerplate to move her foil forward even more:
You can see that the Powerplate here moves the mast forward by about 2 inches. In total, the COL for Nina's setup is about 3-4 inches further forward than for my setup!
So the obvious thing to try is to move the front wing for my setup further forward. I did this by drilling a new hole into the fuselage exactly 2 inches behind the rear hole for the "C" position. By using these two holes, I now have a "D" position where the front wing is moved forward two more inches:
You can see that the COL has moved forward to be closer to the middle of the foot straps. When I tried this setup, it worked a lot better. The foil came up a lot earlier, and it felt more balanced when up. But please note that the extra hole weakens the fuselage, and that the larger distance makes it more likely that the fuselage will bent! So I'm not recommending that you copy this approach!
When I replaced the powerbox in my Skate with a foil box, I put the foil box at the same position that the powerbox had been in. I actually had tried to use the Skate 110 for foiling before, and it had worked well enough - but I completely forgot that I had used the Powerplate, which moved the foil forward! In hind sight, I should have just added a couple of US fin boxes to the Skate 110 for use with the Slingshot pedestal mount. Adding the tracks so that they partially overlapped the powerbox would have been easier than using the foil box, and given me some adjustment room (in addition to the option to mount the mast in the A or B position). That would have made it easy to fine-tune everything for a perfectly balanced setup.
One thing that perhaps let to my confusion about the box placement is that the "C" position works very well with my slalom board:
I don't use foot straps on this board for foiling, so I placed booties where I usually put my feet. The back foot is usually all the way back against the strap that I use to attach a safety line to, and the front foot placement varies a bit depending on conditions and power. But it is easy to see that the distance between COL and back foot is more similar to Nina's setup than to my "unbalanced" setup shown in the second picture.
A closer look at the footstrap placement on the different boards reveals a significant difference: on the slalom board, the back strap positions are about 2 inches further back than on the freestyle board. That's true for the boards shown, but also for several other (newer) Fanatic slalom and freestyle boards in the garage. On some foil boards like the Slingshot Wizard, the back straps seem to be even further back, so that the back foot is where the mast is. Here's an image of the Slingshot Wizard 125 with the foot strap position highlighted:
For comparison, here's an image of a typical freeride board:
The back footstraps are several inches forward of the fin / foil box, similar to what we saw for the Fanatic Skates.
So, if you'd want to use a Slingshot Infinity 76 foil with a Wizard 125, the consensus is that the mast should be in "B" position on the fuselage. For use with a typical freeride board where the footstraps are further forward, the mast has to be in "C" position for the i76.
For the Slingshot Infinity 84 front wing used with a Wizard, the foil should be mounted in the "C" position. This means that use with a freeride board would require a "D" position! Since the fuselage does not have a "D" position, anyone trying such a setup will likely be disappointed (or has drill an extra hole).
Interestingly, Fanatic has chosen a more forward footstrap position for their foil freeride board, the Stingray:
There are lots of option to mount the rear straps, but all of them are pretty far forward. This makes sense, since Fanatic also sells several "foil ready" boards with similar strap positions. All these boards need to work well with the Fanatic foils. Compared to the Slingshot foils, the Fanatic foils have the front wing mounted further forward (the mast is further away from the front wing), which is necessary for a balanced setup.
If you buy a matching foil and foilboard from the same brand, this is not an issue, since you should be able to simply follow their setup instructions. But it you try to "mix and match" foils and boards, subtle differences like a 2-inch variation in the footstrap placement can make the difference between a setup that works beautifully and a setup that is barely useable. Similar issues arise from the position of the foil on the fuselage. For example, RRD freeride foils have the mast mounted close to the middle of the fuselage, while the Slingshot Infinity foils have the mast closer to the front wing, even in "C" position.
For board conversions, some of these problems should be avoidable by going the mast track/pedestal mount route, especially for Slingshot Infinity foils. Whatever option you choose, though, I suggest to check where the front wing will end up before you start the router!
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I have contacted Slingshot with a suggestion to add a "D" position to the fuselage, and heard back from Wyatt Miller, their windsurfing guru. He said moving the mast further to the center increases the chances that the fuselage would bent, since it has more leverage. Nor does it help that the extra hole weakens the fuselage! Apparently, jumping with the larger front wings (Infinity 84 and 76) can bend the fuselage even in B or C position, so Slingshots suggests to use smaller front wings for jumping and things like loops. I had actually noticed a bit of new instability when using the "D" position, but the i84 is always sensitive to water movement caused by chop and swell, so it's hard to tell if this was caused by increasing the distance between wing and mast. To be on the safe side, I'll add a track mount to my Skate.