The angled junction of the two fin blades, with the base, may also act like a smaller version of the ''winged keel'' fin favored by Horan. Looking at the fin convinces me that you are going to have good time surfing it. The more I look at it, the more I like it. I hope your prototype holds together for you. In 1966 I did a winged tip single fin. The forces were so great the wings kept snapping off, and I lost interest in it. If yours breaks up, stick with it. I really think you are on to something, with your design.
The angled junction of the two fin blades, with the base, may also act like a smaller version of the ''winged keel'' fin favored by Horan. Looking at the fin convinces me that you are going to have good time surfing it. The more I look at it, the more I like it. I hope your prototype holds together for you. In 1966 I did a winged tip single fin. The forces were so great the wings kept snapping off, and I lost interest in it. If yours breaks up, stick with it. I really think you are on to something, with your design.
Yep, I thought the same (about the "winged keel") when I sketched this one up. I have a "winged keel" as well which I use when the conditions suit. I was a little unsure about "mixing" the two effects (your twin and horizontal control elements) into the one fin but figured there was only one way to find out.
And it's your design Bill - not mine !!! - I just stuck them together.
Speaking of the Velzy V-Fin, does anyone have some first hand experience with how they perform in short boards ? I'm guessing quite a bit (too much) of lift at higher speeds.
OK, I'll take the bow for the paired, close proximity, fins. But, the way you have married that concept to a single base, in a single box, is yours. The fin shape you have chosen is quite functional, and eye pleasing, IMO. So, don't be shy, take a bow for what you have accomplished. I'm waiting to hear your ride report now!
I rode my board (shown on the first page of this thread) with standard 9" cutaway fins because thats what I had. I didn't have any problems with the board in any of the waves I rode. The nose had a lot of belly so it didn't work well stepping way up there. Turned great and enjoyed riding it. I never added a leash holder to that board, so it says a lot about the confidence I have in it working good enough that won't be swimming much.
One thing I didn't like is that I made the board just a bit wider than I can comfortably carry under my arm. Nothing bad about performance, just don't like carrying boards that don't fit under my arm. I haven't been riding that board for a while because I am using the fins on other boards.
I think this fin setup might be fun on a longer pig shape, where you'll be doing a lot of turning but could also run up to the nose and do some tip time. I think I'll stick to fins closer to the rail for short boards.
Thanks for the kind words Bill - and for providing the inspiration to try this.
I've only ever made a couple of fins before attempting this one - but after first seeing this thread a couple of years ago I just couldn't get it out of my head.
I'm hoping to get it finished in time to take to Bali soon. I will be surfing it in an old home made small double ender style board which is based on the 7' McCoy shown in the images - minus 8" cut off the nose.
"Considering will how long it takes to lay out and rout out two additional fin boxes, plus the risk if weekining the tail, it would be easier to fabricate a double fin that would fit into an existing single fin box."
My take on single fin boxes is that during the installation the stringer is almost completely routed through and can create a weak spot immediately in front of the box. I've seen many boards snapped right at that spot. It is possible that by routing box slots on either side of the stringer, the overall strength in the tail might be enhanced.
Fabricating fins can be a pain. The Velzy V-Fin is the only double fin/single tab fin commercially available as far as I know. Standard single fins are readily available worldwide.
Maybe Thrailkill is in on box distribution royalties? HAHA
I read somewhere that while George Greenough was experimenting with his fin placement he started out with conventionally placed twins but gradually placed them closer and closer together (with improvement) until he just decided that a single would work best. Maybe his assumption led him to bypass the closely spaced setup at which Bill arrived?
Sailors are aware of the 'slot' effect that occurs between main and jib. Some surfers swear by certain quad placements - maybe for the same effect? Perhaps something similar is occurring with the Thrailkill twin?
RDM,
The angled junction of the two fin blades, with the base, may also act like a smaller version of the ''winged keel'' fin favored by Horan. Looking at the fin convinces me that you are going to have good time surfing it. The more I look at it, the more I like it. I hope your prototype holds together for you. In 1966 I did a winged tip single fin. The forces were so great the wings kept snapping off, and I lost interest in it. If yours breaks up, stick with it. I really think you are on to something, with your design.
Bill Thrailkill
SHAPER SINCE 1958
Yep, I thought the same (about the "winged keel") when I sketched this one up. I have a "winged keel" as well which I use when the conditions suit. I was a little unsure about "mixing" the two effects (your twin and horizontal control elements) into the one fin but figured there was only one way to find out.
And it's your design Bill - not mine !!! - I just stuck them together.
Speaking of the Velzy V-Fin, does anyone have some first hand experience with how they perform in short boards ? I'm guessing quite a bit (too much) of lift at higher speeds.
RDM,
OK, I'll take the bow for the paired, close proximity, fins. But, the way you have married that concept to a single base, in a single box, is yours. The fin shape you have chosen is quite functional, and eye pleasing, IMO. So, don't be shy, take a bow for what you have accomplished. I'm waiting to hear your ride report now!
Bill Thrailkill
SHAPER SINCE 1958
woohoo !!
thanks for telling me about this , Rowan
A ride report thread when you've tested it in bali waters ?
q: HOW do you foil INSIDE edges , do you make two fins , foil them identically , then join them together or something , Rowan ?
cheers
ben
" I hate it when I don't know the answer! " [bill thrailkill] ... heehee
..... i actually LOVE it when i don't know the answer , because it means we are always able to learn more !
I rode my board (shown on the first page of this thread) with standard 9" cutaway fins because thats what I had. I didn't have any problems with the board in any of the waves I rode. The nose had a lot of belly so it didn't work well stepping way up there. Turned great and enjoyed riding it. I never added a leash holder to that board, so it says a lot about the confidence I have in it working good enough that won't be swimming much.
One thing I didn't like is that I made the board just a bit wider than I can comfortably carry under my arm. Nothing bad about performance, just don't like carrying boards that don't fit under my arm. I haven't been riding that board for a while because I am using the fins on other boards.
I think this fin setup might be fun on a longer pig shape, where you'll be doing a lot of turning but could also run up to the nose and do some tip time. I think I'll stick to fins closer to the rail for short boards.
Thanks for the kind words Bill - and for providing the inspiration to try this.
I've only ever made a couple of fins before attempting this one - but after first seeing this thread a couple of years ago I just couldn't get it out of my head.
I'm hoping to get it finished in time to take to Bali soon. I will be surfing it in an old home made small double ender style board which is based on the 7' McCoy shown in the images - minus 8" cut off the nose.
Cheers
Rohan
Really great thread...... props to all the seekers.
"Considering will how long it takes to lay out and rout out two additional fin boxes, plus the risk if weekining the tail, it would be easier to fabricate a double fin that would fit into an existing single fin box."
My take on single fin boxes is that during the installation the stringer is almost completely routed through and can create a weak spot immediately in front of the box. I've seen many boards snapped right at that spot. It is possible that by routing box slots on either side of the stringer, the overall strength in the tail might be enhanced.
Fabricating fins can be a pain. The Velzy V-Fin is the only double fin/single tab fin commercially available as far as I know. Standard single fins are readily available worldwide.
Maybe Thrailkill is in on box distribution royalties? HAHA
I only WISH that were true!
Bill Thrailkill
SHAPER SINCE 1958
I read somewhere that while George Greenough was experimenting with his fin placement he started out with conventionally placed twins but gradually placed them closer and closer together (with improvement) until he just decided that a single would work best. Maybe his assumption led him to bypass the closely spaced setup at which Bill arrived?
Sailors are aware of the 'slot' effect that occurs between main and jib. Some surfers swear by certain quad placements - maybe for the same effect? Perhaps something similar is occurring with the Thrailkill twin?
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