Help with Fin Repair 1977 Fish

Hi guys. I bought a 1977 Sunshine Rocket Fish Twinny. I need some help fixing the fin pictured below.

Check out in each pic where the pencil tip is pointing. I have lots of experience repairing dings but am not

sure how to fix this old fin. The fin is stable and not wobbly. Do I just pry off the cracked glass and recloth over the stable old glass?

What oz do i use for the cloth? Also-the swallow tail needs some repair-does anybody know a way to match the new repair

glass to the "yellowed" color of the board? Thanks for your help!














Cannot see any pics

sorry. weird. how bout now?


OK . I can see the pics, now. You should grind out the damage at the base of the fin and lay some rope in there. Once that sets up, sand out to match the curve and glass with two layers of 4 oz. At least, that’s how I would do it.

Don’t have fiberglass rope? Make your own. Get some 10 oz cloth, cut it into 4x4 squares,  and pull out strands to make a bundle about 1/4" to 3/8" thick.

Search this forums archives as to how you do fin rope at the base.

A crafty guy I know (named “Doc”) uses coffee to tint resin so it matches older boards that have yellowed. You’ll have to go with trial and error on that one.

Thanks for your input.  I was just looking at the board- the fiberglass under the crack in pic #1 (where the fin meets the board)

is stable and the fin is snug. Do you still recommend using the rope? Also-what is the best tool for "grinding" the glass?

I have a dremel at my disposal......thanks again.

I did the search for you. Ball’s in your court, now.

damn. i would like to do this fix myself but dont want to screw it up. what do you guys think

a surf shop would charge to fix it?

If you don't take the risk of screwing up then you will never learn anything ! Chance um !

Uhmmm- put it this way, what a surf shop would charge for labor is a big piece of what you'd pay for the tools to do it, and there really ain't that many. Here's your tools and materials list

Scissors - not real good ones, the plastic-and-stainless ones are good enough

Throwaway 1" chip brushes, the ones with natural bristles

Sanding resin- maybe 8 ounces/half a pint.

6 oz. fiberglass cloth

Fin rope

Paper cups

Stir sticks, the wood ones

Random orbital sander with discs ( this is optional, look locally for a used one from Porter Cable or Milwaukee or Bosch. You don't want the palm grip, hold-in-one-hand type)

80 grit sandpaper

Wet sandpaper, several grits.

Utility knife or X-Acto knife with new blades. 

Vinyl gloves, the cheap ones from the hardware store

Masking tape

Okay, here's what you do -

Carefully sand the loose and cracked cloth away. Take your time. A random orbital sander will make it easier, but you can do it by hand, it takes longer but if you're not familiar with power tools, this prolly isn't the place to learn from scratch.

And no, I don't consider a Dremel to be a power tool, it's only a hobby thing for doing eensy weensy little things, not ding repairs. Neither are the sandpaper disc setups that Uncle Fred used to put in a drill. Uncontrollable, with those things you wind up doing more damage than you fix. But I digress.....

Once you have the cracked and obviously loose stuff deal with, that's when you go with the rope . Like SammyA said, you can make your own, from 10 oz cloth or woven roving scraps.

Now, here's a trick. Use maybe one crystal or so of instant coffee stirred into your sanding resin, most of a cup of it. It's a brown tint and not much more, not unlike instant coffee . Don't catalyse the whole thing, just use a little in another cup, catalyse that lightly and stir well, and with your vinyl gloves on put the fibers in place alongside the fin base, brushing a little resin into 'em until they are translucent, clear.

I say catalyse lightly 'cos that gives you more time to work with it. If the stuff goes off too soon, you have a nightmare to sand away and it's really no fun at all. I say put the tint to a cup full of uncatalysed resin ( cover it between steps) so you don't wind up with four different tints for every step.

Kinda gently mold the fin rope-resin glob with your gloved fingertip so it's concave. That will save you a lot of sanding later. When the resin goes to a gummy, gelatinous stage, that's the time to get any stray drops and blobs up, they should peel off nicely.

Okay, sand the hardened glob ...when it's hardened. Use the 80 grit, make it a smooth transition between the vertical fin and the horizontal bottom. That's its function, you see, to make what's ttechnically called a 'fillet' between 'em that looks good. No lumps, no lines, just smooth.

Now, wasn't that fun? Good, now for the next step. Take your scissors and cut some 6 oz cloth that are more or less the same size as the fin plus an inch or two to lap down onto the bottom. Same scissors, cut the bristles shorter on one of your brushes, to maybe 1" long. Catalyse some more resin, brush a little onto the surface you're gonna glass, set cloth on there, brush more onto it, set your next layer, more resin until the cloth is clear but the weave still shows. Leave it at that, let the resin dry some, until it's nostly hardened,

Now take your x-acto knife, the Really Sharp one and cut the cloth away that sticks past the outline of the fin. Okay,  wait until it's as hardened as it's gonna get, sand the edges of your cloth so there's a nice smooth transition.

Right, mask around where you sanded the transitions on the bottom and with your last throwaway brush, brush some catalysed resin onto your new cloth and the spots right adjacent to it. You're looking to fill the weave of the cloth and blend your transitions, no more. I'd go a little stronger with the catalyst, so it will harden before it sags away.

When that has hardened, break out the wet sandpaper and sand it nice and smooth, maybe go to 400 grit. It won't be perfectly polished, but then again, this isn't a museum restoration or a new board, it's your first ding repair and you're gonna use the board, right?

Okay, have at it. And I need to have my coffee and get the old brain going.

hope that's of use



Instant coffee…

Doc, you’re the man…

Only decent use for the stuf, as it's undrinkable. Kinda like Starbucks - and it dissolves in acetone ( for polyester resin ) or alcohol (for epoxy) .  Though I haven't seen any really brown epoxy boards as yet.


Thanks for your help guys. This isnt my first repair, but it is my first fin repair. I have in the past joined two broken halves together with dowels, etc. I know a little bit anyway...:)...even shaped a board once (didnt have the balls to glass it though-used an outside source)

My only unanswered question is this-and maybe you all are answering it...should i really get rid of all the stable, good fiberglass under the crack at the base of the fin (aka where i would put the rope)? The fin is really stable....



Ahmmmm- okay, well, putting the board together with dowels was an error, but in any event....

No, if it's sound glass, leave it alone and don't bother with fin rope there, just sand away at the stuff further up that is loose, then a layer of glass to do that up and you should be okay. Never grind off something that's still good if you can possibly avoid it.

hope that's of use


Cool. Thanks doc and all those that helped me.  The board i joined with the dowels was just a buddy's he was gonna throw out after a big swell broke it.  It actually came out ok, and I was amazed i even got the rocker and rails to match up. Nearly killed my parents though with the fiberglass fumes going up through the garage floor though! Anyway...thanks again. Appreciate the coffee tip too.