One for the brains trust...

Got a tuttle box fin that currently sits too deeply in a deep-tuttle box. I've no idea if the fin head us undersize or the box is oversize, but it's sitting about 1mm beneath the board base.

Any tips or tricks for bulking out the fore and aft end of the fin head to bring it up flush with the bottom of the board? (The bulk required is too much to be accommodated by just some layers of tape).

The bulking out with fibreglass and resin (potentially in several steps) is not complicated, but I'd love some wisdom on how to maintain the right radius and straightness of the bulked out areas to ensure nice, even pressure distribution and transfer from the fin to the box. Are there any moulds or jigs that are useful or does one just bulk it out roughly and sand back carefully by eye to match the box shape as best as possible?

Thanks...

Shelley's knead it, is good stuff.

Clean one end with a light sandpaper. With a brush paint on a layer of Araldyte. Because it is quite thick it should add about 0.3mm which should be plenty. If not both sides . Sand back if its too much.
Personally i wouldn't worry about 1mm , 2mm i would .
I wonder at what depth one can feel the drag of a sunk in fin or if it creates cavitation ???

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Imax1 said..
Clean one end with a light sandpaper. With a brush paint on a layer of Araldyte. Because it is quite thick it should add about 0.3mm which should be plenty. If not both sides . Sand back if its too much.
Personally i wouldn't worry about 1mm , 2mm i would .
I wonder at what depth one can feel the drag of a sunk in fin or if it creates cavitation ???

Id rather have a 3mm sunk in fin than one that sits 0.5mm proud. In the never ending quest for speed though...

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Imax1 said..
Clean one end with a light sandpaper. With a brush paint on a layer of Araldyte. Because it is quite thick it should add about 0.3mm which should be plenty. If not both sides . Sand back if its too much.
Personally i wouldn't worry about 1mm , 2mm i would .
I wonder at what depth one can feel the drag of a sunk in fin or if it creates cavitation ???

And if you want to get fancy, throw some mill fibre in with the mix.

more fancy would be resin and aluminium dust, ridiculously harder wearing.

I agree that 1mm too deep is not a concern.....

However to get it spot on you could wax the inside of box and insert fin the right depth with filler on the ends. Then you are literally moulding that fin head to the box. Clean really well after as you don't want slippery box, its a taper lock...

Or you can cut strips of plastic from a milk bottle. Use the corners of the bottle to get a lengthwise curve on the strip. 15mm wide, as long as you need (30mm?), slide the strip in with your fin. Flush fin fit the easy way.

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Te Hau said..
Or you can cut strips of plastic from a milk bottle. Use the corners of the bottle to get a lengthwise curve on the strip. 15mm wide, as long as you need (30mm?), slide the strip in with your fin. Flush fin fit the easy way.

+1. I use strips of yellow plastic cut from the lids of Margarine containers. Hold them on the fins for fitting with a dob of any glue.

If that 1mm really bugs you, but the fin fits fairly well where it does (albeit deep), why not just built up the top of the fin head (next to the fin) instead of the sides? Way more easier, much smaller job, w/o any fear of it breaking down under pressure because it isn't under any.

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Mastbender said..
If that 1mm really bugs you, but the fin fits fairly well where it does (albeit deep), why not just build up the top of the fin head (next to the fin) instead of the sides? Way more easier, much smaller job, w/o any fear of it breaking down under pressure because it isn't under any.

^^^
That got me thinking , If your going to do this , would it be better to add a nice radius from base to fin like a dolphins fin would ? You dont see that on fins its always a sharp non flowing type right angle ?
Whats the go , i would think a nice flowing join would be best ?

^^^ weed wave

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Imax1 said..
^^^
That got me thinking , If your going to do this , would it be better to add a nice radius from base to fin like a dolphins fin would ? You dont see that on fins its always a sharp non flowing type right angle ?
Whats the go , i would think a nice flowing join would be best ?

www.seabreeze.com.au/forums/Windsurfing/Gps/FangyFin-MkII-Theory-for-insomniacs?page=1

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NotWal said..

Imax1 said..
^^^
That got me thinking , If your going to do this , would it be better to add a nice radius from base to fin like a dolphins fin would ? You dont see that on fins its always a sharp non flowing type right angle ?
Whats the go , i would think a nice flowing join would be best ?

www.seabreeze.com.au/forums/Windsurfing/Gps/FangyFin-MkII-Theory-for-insomniacs?page=1

^^^
Yeeeesssss , just like that

Te Hau - your milk bottle suggestion using the precurved corners of the mild bottle for easy fitment was a pearler! One strip front and back and the fin is a beautiful, flush fit. Thanks All.