Tri Fin to Quad Fin

General Discussion
1

Hello fellow surf addicts,

 

After many frustrating fin breaks I’ve decided to convert my tri fin 6’ 4" Walden Fish into a glass-on quad fin. The fishboard is pretty sweet as it is so easy to ride. However I felt that the speed of the board was greatly reduced because of the trailing tri fins. Its made to be converted from twin to tri. Can I glass in quad fins? If so, how do i figure out fin placement? Also…at what angle to camber the fins? 4 degrees or 8? less or more? How does fin angle effect performance? Also how would i measure the angle since the board is concaved? 

 

Anyother tips are greatly appreciated. 

The board can be seen here : 

http://www2.swaylocks.com/forums/walden-fish

 

 

2

Why not just ride it as a twin?  It looks like it was set up with that option in mind.

3

 

Well my friend. Thank you for the suggestion. However I’ve already ripped out the plugs and prepped the area for glassing. Also, Im just not a twin fin kind of guy. Too loose and a lot of power lost in the drive. Quads are kind of the next evolution from twins. My suggestion is why don’t u try a nice set of quads sometime?

 

4

[quote="$1"] ...I've already ripped out the plugs and prepped the area for glassing. Also, Im just not a twin fin kind of guy. Too loose and a lot of power lost in the drive. Quads are kind of the next evolution from twins. My suggestion is why don't u try a nice set of quads sometime? [/quote]

Just a question to keep the conversation going, no insult intended.  I have three quads, one converted from a twin, one glassed but not finished, and one ready to glass.

5

i usually set up my trailer fins at 5 degrees

and here is how i meassure the angle[img_assist|nid=1062134|title=fin installation|desc=|link=none|align=left|width=386|height=261]

 

 

 

 

 

 

 

 

 

 

[img_assist|nid=1062135|title=fin installation|desc=|link=none|align=left|width=388|height=262]

 

 

 

 

 

 

 

 

 

6

thanx SD! The pictures tell it all! SO much help. Im glad i get to chat with the pros! As far as fin angles go, have you experimented much with varying the angles? Does 0 degrees mean stiff and 8 degrees mean not enough grab on the wave face? 

 

 

 

 

 

 

 

7

 

So you’ve had experience converting? Do tell. What are some tips you can share. I’ll post some pics of the finished job. Phase 1 of my project is so disgraceful I’m embarrased to show the sloppy work. 

8

[quote="$1"]

So you've had experience converting? Do tell. What are some tips you can share. I'll post some pics of the finished job. Phase 1 of my project is so disgraceful I'm embarrased to show the sloppy work. 

[/quote]

Not really.  I converted a retro fish to quad, but haven't really had a chance to test it.  I tried to get some straight answers on the best way to convert, but found the subject was too subjective for there to be a right or wrong answer.  So I just went for what made sense to me. 

The board has been converted for awhile, but I've been busy riding other shapes, when I've had the opportunity for a go-out, I don't get out in the water a lot.  One of the problems of having too many boards, and not enough time to surf them LOL.  I tried to get a rider to test my boards for me, but that didn't really work out either, another story.

Here's the thread http://www2.swaylocks.com/forums/can-retrofish-be-converted-to-quad-fish-adding-2-more-fins?page=2

I took the board out at small Malibu awhile back, with just the two fins, after they were cut down from keels.  It rode great, but a bit too lose (it tracked before, so loose is good).  Then I put two more fins in, but as I did, I noticed I need to work on the cut-down fins a bit.  I really didn't spend much time on them, and I noticed there is raw wood at the edges as a result of cutting them down, so I have to seal the edges a bit better. 

The pic shows sidebite fins in front, but if I use standard thruster fins, then all 4 fins are pretty much equal in size.

I don't have any real ride report yet.  I used probox fin plugs, that way I can adjust the angle of cant with different inserts. 

The board is in my growing "needs a bit of work" pile, meanwhile I've been riding my 9' longboard when I get a chance to go out, because I felt that constantly changing wasn't such a good thing, I've been trying to stick with one board for awhle.

9

Dude…that is friggen sick. Whats the size? It looks awesome!

My theory is that the glass ins add down the line thrust and prevent alot of roll. The side bites add stability where otherwise there would be too much yaw. Then you have that fat channel in the middle for water flow. I would be very curious as to how it rides. Send it up to Santa Cruz and I’ll let you know. LOL.

 

 

10

 

Well… Below is the progress. Pulled out the fin system and sealed it with Q cell, fiberglass and now a hot coat. Its ready to sand and polish. 

Then I’ll mount the quads. 

Question for someone:

What should I do if the hot coat is not completely cured? I repaired a whole bunch of other dings with fiberglass and hot coat however my last batch of resin I think had a few drops too little of MEKP. Now the hot coat is sorta slightly sticky to the touch. It does sand however. Do you think it’ll be good for water? The stickyness is like 97% dry and 3% sticky. So much so that if you press on a patch you’ll leave a finger print trace. 

Really don’t want to have to strip the board again and re hot coat. lemme know. Shakahs. 

 

 

 

 

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11

 

Well… Below is the progress. Pulled out the fin system and sealed it with Q cell, fiberglass and now a hot coat. Its ready to sand and polish. 

Then I’ll mount the quads. 

Question for someone:

What should I do if the hot coat is not completely cured? I repaired a whole bunch of other dings with fiberglass and hot coat however my last batch of resin I think had a few drops too little of MEKP. Now the hot coat is sorta slightly sticky to the touch. It does sand however. Do you think it’ll be good for water? The stickyness is like 97% dry and 3% sticky. So much so that if you press on a patch you’ll leave a finger print trace. 

Really don’t want to have to strip the board again and re hot coat. lemme know. Shakahs. 

 

 

 

 

12

Poly resin or epoxy? If its poly did yout use waxed resin for the hot coat? Good luck with the project quads are fast

13

A little late now…  You may have been able to add more fin box/plug options.

I am a fin box convert - the adjustable kind, 4way, RedX, etc…  There is much to be learned and gained by being able to adjust and change fins.

Good luck.

14

Sticky like taffy, or sticky like hard candy?   If sticky like taffy, wait..if you put cat in it..it will kicks, might take a week, but it should kick.  if sticky like a coating on candy, then you used lam resin and it's meant to stay sticky.

Go to your moms kitchen drawer and get some wax paper, put the wax paper ocer the surface thats sticky, let that stay for a while and see what happens.

If not go to the store and buy lots of san paper...lots of sand paper.

I got to ask, what made you rip out the boxes, and not just route out new holes through and around old boxes?  Router bits go through old fin boxes real good, just make sure theres no metal screws hiding around.

And you took on a big project for one of your first ones?  Re-finning a board (re-designing) is a big step in surfboarding..probably one of the most intricate.

 

I wish you the greatest of luck in your challenge.

15

Wow…the shaping Guru’s have spoken. You guys are awesome. Thank you soo much for the advice. BTW. How did you know I lived at home? yes. I am a bum. ha ha ha. Actually not really. 

I definitely will by a router for next time. But as you said. I’m a newbie. Took on the challenge because I really wanted to and I think I can do it. Plus i’ve filled billions of dings. 

 

More Q’s

  1. The quads i have are all the same size. Whats the difference between varying sizes of fins?

     ex. small sidebites and large inner fin. or vice versa.  

  1. Whats your experience on adjusting cant

     What would be a good angle? Also I’ve seen different cant angles for each fin. 

           ex. sidebites at 6 degrees and inner fins at 4

  1. How about toe? 

 

 

 

Thanks!

 

 

 

16

try this

http://www2.swaylocks.com/forums/few-quick-quad-questions

and this

http://www.mckeesurf.com/brucemckee/multisystem.htm

huge amount of info on this site about quads