Carafino board inside

[tkettlepoint]

Tomi there are a couple of ways to fix / do a reg surf board mount.

The way I would do it is get a block of corecell 1"-2" bigger then the mounting plate all the way around and as thick as your board. crave the foam out so it fits in tight where the plate was screwed. Put your interest in the block , but put some glass under/ around them with some epoxy before you put it into the board . glue it in with a good polyurethane glue which is swell up and fill any spaces. ( broken board) on the out side of the block put a couple of stringer in 12"-18" long once again polyurethane glue them in too.

I hope this helps
terrie
www.jellyfishboards.com

[BigTomi]

Tomi there are a couple of ways to fix / do a reg surf board mount.

The way I would do it is get a block of corecell 1"-2" bigger then the mounting plate all the way around and as thick as your board. crave the foam out so it fits in tight where the plate was screwed. Put your interest in the block , but put some glass under/ around them with some epoxy before you put it into the board . glue it in with a good polyurethane glue which is swell up and fill any spaces. ( broken board) on the out side of the block put a couple of stringer in 12"-18" long once again polyurethane glue them in too.

I hope this helps
terrie
www.jellyfishboards.com

Hey Terrie

I think your way is good way to do it. After some googling around I found that method you describe is mostly used. I might do same think to old board as well, just to see how will go.
Thanks for info , will post any results.

Tomi

[BigTomi]

Here is progress of repair

Comments and suggestions welcome

[Nielshm]

To secure your longitudinal strength of the board no need for such a thick stringer. 10 mm would have done fine. They are incredible strong when kept in place by foam and glass.
All the forces from the foil (pressure up on the board) will be maximized right on the front corners of the front bolts. Probably also a considerable amount of torsion. This means all the forces will need to travel from the bolts to the stringer through the board. As you have placed the stringers away from the bolt pattern your weak spot is right between.
I would strengthen the area between front bolts and the stringers. A plate or fiberglass will do fine to transfer force.
Local foil surfer had his foil ripped out on exact same construction this Saturday...(foil is now sleeping with the fish)
As safety measure you could drill a thread in one of the bolts and put a eye with a line to the footstrap. Just in case...

[zfennell]

-new glass needs to overlap entire perimeter of failed joint (top and bottom)
at least 2" on each side of crack. ( 4" on each sde with varying laps would be better)
-crushed core inside needs to be removed and replaced
-remove paint and pads (down to just resin and glass) wherever you end up glassing

thinner stringers that go full depth will better tie top and bottom skins
additional thin stringers/reinforcement that tie directly to mast area would help distribute load, stabilize skin and tie top to bottom
-better would be a thin sandwich skin to resist buckling or a denser core thru the full thickness
-..030" -050" of wood veneer with 4oz glass could suffice structurally while cosmetically hiding the repair underneath ( and weigh less than the planks you are currently using)

this is a buckling problem.
i.e. the mast tries to dent the bottom while your feet try to bend the top.
in this case, the mast won.

once the bottom skin buckles/dents, the top skin can no longer support the bending loads from your feet and pops



stabilise the bottom skin, so it does not become 'dented' by the foil mast.

imo

[BigTomi]

Stringers groves already cut, so can't get them smaller it is 2x2cm and connects both skins.
Carbon fiber applied in side groves and than stringers laminated in place.
Once dry whole lover skin will be sanded down to fiberglass flat and carbon fiber laminated in 4 layers reducing in length from front of stringers to aft to form new bigger base plate cowering rails as well.

Upper skin I guess 3 layers will be more than enough.

This is my first build so it my be a bit oversized but better than losing foil.

Thanks guys for yours advices it is really appreciated.

Tomi

[zfennell]

will the glass on top cover the same area as the glass on the botttom?
particularly in the area of the failed joint. (4" overlaps) ?

you may consider replacing the wood blocks with foam that is wrapped in glass.
(wet them, wrap them, push in place)
that would reduce the density of the filler material by a factor or 4.

do your inserts really go all the way to the top skin?
again, especially near the foil mount area?
scrape out all that white (eps ?) foam to get a secure bond

its not too late to consider Terrie's suggestion of a structural foam insert (diivinyl cell ,corecell ) to replace current mast base.

i realise you only consider this to be a 'salvage' effort.
but much of the above, would be part of accepted skill set for structurally sound construction in the future.

have fun,
-bill

[BigTomi]

Great suggestion.

Regarding stringers already cut grover, so this time will let them stay oversized.

Decided to remove all foam over base plate and build new mast base fixture with new block of core cell foam laminated in sandwich with carbon fibber between stringers. Both new base plate insert and stringers connect both skins clearly with out any old foam in between. After that all laminated in 4 layers on lower skin and 3 on a top.

Did not plan to go in such extensive repair, but after considering yours advices decided to go with prober detailed repair.

will post some pictures before skin lamination.
This will be at least good learning process before building new board

Thanks guys for suggestion and guidance.

[zfennell]

very good.
as this is still a learning process, i would add a few more comments.

give some thought to all the new 'parts' you intent to add to the repair.
how does their function interact with other components?
does the addition of one negate the need for the other?
can you redistribute or replace w/o penalty (or possibly gains)?

weigh each part . wood, glass, foam,resin, etc. before adding to the board.
especially the amount of resin (just about everythig will get twice as heavy even if you're careful where the epoxy goes.)
dont let a gallon of resin get sucked into the eps core.

weigh the board after every step is cured.
track each step
grade youself using metrics like cost, weight , performance, labor, etc.

when its all over, i'm sure it will still work fine.
but it may weigh as much as a 4x8 sheet of plywood from home depot

we always criticise the manufacturers for what went wrong. but an awful lot of stuff must have worked out ok for the board to last 4+ years.
dont lose track of all the good parts of the original design.

no worries,
-bill