Glassing on Longboard fins

Hi everyone, I’m in the final stages of building a 9’7’’ old style log for a friend and he has decided to have a glass on fin instead of a box. The fin is a fibreglass 10’’ Pivot style fin placed 6 inches off the rounded square tail… I have never glassed on such a big fin before and need advice on the procedure…ie. what weight glass, how many layers, etc. Do I cover the entire fin? or just half way up? I’ve done a search and have only found links to doing fin repairs etc on short boards, but found nothing on glassing on longboard fins like pivots or D fins. 

Thanks

The fin you are proposing to use is waaaayyy too much fin!      Is this your idea, or the customers idea?     Also nuts not to use an FU box.     At least with a box an inappropriate fin situation is easily corrected.     But then, what do I know, eh?

 

Agree on both counts. Some very specific designs lend themselves to a glass-on. But a standard longboard, or any single fin that needs some versatility, should have a fin box. Why limit your options?

Or, as Bill points out, what if the fin chosen doesn’t mesh well with the shape it’s on? Ya gotta cut the damn thing off and start over.

I get the feeling that some folks want a glass on for so-called traditional logs just because that’s what really old boards had. By 1966 just about every name brand surfboard offered a removable fin system.

“Old school” is one thing, ill conceived regression is something else.

11 inches was a typo mistake sorry… meant to be 10. Why do you say it’s too much fin… I run these type of fin on my own boards both in boxes and glass on with great results.

I respect your opinions guys, but Iets stay on track here. I want good info on the process of glassing on a big fin, not a debate on which fin is right or wrong.

   Why do I say it’s too much fin?    Why, indeed?    How about, ‘‘Considerable experience has demonstrated that to me.’’    take a look at my avatar photo.    That’s a 10’ 3’’ board, with a 7 inch deep fin.    Plenty of control, plenty of drive, and no spinouts anywhere on the wave.    Now, if you’re happy with the way an overfinned board rides, then soldier on.   

Bill

You’re on your own.

I’ll make an attempt to help the OP.  I just did a glass on of a 9" fin last week.  Tail patch lamed into the board.  Fin rope followed by 2 layers of 6oz and a layer of 4oz.  Seems good and strong and we’ll see how it holds up to the abuse this board will get navigating the crowds of summer kooks.

Football shaped patches of glass cut on the bias. Double the height of the fin. The outline of the patch can be modified, depending on the fin’s profile. Basically, I cover the whole fin and get as much out toward the rail as possible. Lammed onto both sides of the fin and trimmed after gelled. Double 6 oz will do. There are differing viewpoints as to the advantage of using fin rope. To fillet, or not to fillet.

I like my last layer of glass to be a full length piece of 4 oz cloth.  Covers all the other layers and makes it easier for me to foil the whole fin back out without having to sand a distinct ridge.

I do all the glass full coverage. Not a fan of the ridges.

 

I agree.  I’m not that skilled a sander, and a lot of times if I’m working out a ridge, I end up with a small depression on the side of it while sanding it out. End up chasing my tail.

It’s easy to sand through the weave at the edge of the ridge, too. Looks like hell. Why skimp on the glass?

I use roving. Two layers of six ounce full coverage. trim the overhang with a razor when it jells. Been doing it that way for 40 plus years. Hell we used to lay up our own fin panels…cut the outline and glass em on. Did the foiling in the sanding rack with the board on its side in the pocket. Used a grinder with a 60 grit disk. Talk about itch!  It was gruesome.

Same. Used to foil the fins after they were on. Of course, when I was glassing fins didn’t have a whole lot of foil, anyway.

 

Thanks Mako224, Sammy A, Phebus for your direct to the point replies. Pure straight info on the process was all I was needing… You all seem to be on the same track so I now feel comfortable with this way to go.

Thrailkill, Your choice of a 7inch fin for your 10’ 3’’ might be perfect for you and the way you surf, but curious how you can say a 10 inch fin is wrong for this board without… seeing the board…knowing the way it will be ridden, or the type of waves it will be ridden in. Is my friend a guy who is a fanatical noserider who’s home break is a sucky hollow pointbreak or does he just hang on the rear half of the board and do very little walking? Many factors determine what fin should be used and with my own limited knowledge on wave dynamics and fin design I tend to go with what works for the style of board and the way it will be ridden. The late great Donald Takayama designed a 10’’ hatchet fin which was used on most of his noserider models. I can’t imagine why he would use such a big fin if it didn’t perform… just saying. I appreciate everyones input.

cheers

Shane

Sammy, I’ve got 6oz Silane, and 6 oz Volan… Would one be better than the other for this purpose?

For the record guys… I forgot to point out that the "Glass On’’ request came from the client. I did suggest going for a box for ALL the reasons stated above, and they are the same reasons I put boxes in my own boards… I’m a fin “junkie” and like to try all sorts of heights and designs in a board, but if your client is firm on their request, then what can you do? 

 

Use the Silane or you will see the laminations you use to lay up on the fin. Silane will be invisible.

https://www.youtube.com/watch?v=hrvtowbDuDI

 

I prefer a tail patch on the bottom of the board(if doing a large single fin), and then laying up football patches on each side(2 patches on each side, starting with the largest, working up to the smallest).  Then laying a full layer up that covers the entire fin(1" over, then trim).  I also use roving at the base.