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Board Repair - Soft deck crack leaking

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Created by vosadrian 1 month ago, 19 Dec 2025
vosadrian
NSW, 456 posts
19 Dec 2025 10:02AM
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Hi All,

I am about to start my summer break where I like to sail a lot. I went for a sail yesterday afternoon and realised my board (Old 2013 Isonic 97) has developed a soft deck and crack in front of the right front footstrap. Basically about 10cm X 5cm. I can push on on it and see water come out of the crack. I am just after a quick fix to sail over the next few weeks. I can redo the repair at a later date properly. Can anyone point me in the direction of a guide to do such a repair?

Thanks in advance!

Cheers,

Adrian

Imax1
QLD, 4926 posts
19 Dec 2025 10:32AM
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It's a big kind of repair. The first thing needed is to properly, completely dry it. That alone will take a while. Possibly weeks. By just patching over doing a quick fix will spread the water inside and do more damage. Unfortunately, what you're hoping for is not a good idea. Those boards are notorious for getting soft there. Ideally the whole area in front of the straps to the mast base should be replaced. Probably about the same cost as a solid second-hand board of similar age. The quick and easy repair would be to inject a slow curing resin under the soft spot but needs to be perfectly dry. This will take a long time if you don't remove the dodgy area. And that's not a proper fix because that whole area is probably dying. I think you deserve a new secondhand board for Xmas if you want to go sailing now.

vosadrian
NSW, 456 posts
19 Dec 2025 12:21PM
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Select to expand quote
Imax1 said..
It's a big kind of repair. The first thing needed is to properly, completely dry it. That alone will take a while. Possibly weeks. By just patching over doing a quick fix will spread the water inside and do more damage. Unfortunately, what you're hoping for is not a good idea. Those boards are notorious for getting soft there. Ideally the whole area in front of the straps to the mast base should be replaced. Probably about the same cost as a solid second-hand board of similar age. The quick and easy repair would be to inject a slow curing resin under the soft spot but needs to be perfectly dry. This will take a long time if you don't remove the dodgy area. And that's not a proper fix because that whole area is probably dying. I think you deserve a new secondhand board for Xmas if you want to go sailing now.


Thanks for that. I was thinking similar regarding getting a board to use until this is sorted. I started a thread in NSW section trying to see if anyone has one. All the good board options in the buy and sell seem to be interstate.

I have the board in the sun (vent removed) and water is coming out of the crack.... and I discovered similar but less advanced in front of the other footstrap... so it seems the whole area need to be addressed and will take time to repair properly. Also there is water coming out of the vent which is unfortunate as I hoped the water was limited to the one area.

So first prioirty is locate a board to use quickly. If not, I may just continue to sail this board and ride it into the ground so to speak as it sounds like repairing may not be economical unless I do it myself. The board in current condition cannot be worth much. I think it is 2012/13-ish model and I got second hand in 2014. Probably not worth much even if it was in good condition.

Its a hot day today and drying in the sun. Am I better off to attempt to inject epoxy or just keep using it as is? Will some attempt at a quick repair be better than none?

Hydrosurf
260 posts
19 Dec 2025 10:25AM
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If you seal up the board with water still inside it may delaminate if it gets hot. Take the vent out when not sailing.

decrepit
WA, 12776 posts
19 Dec 2025 10:37AM
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this is a flexing point, that's why it's cracked.
Exactly the same will keep happening with "temporary" repairs.
I'm not sure it's worth the trouble.

I don't think Imax is 100% correct, there are epoxy resins that set under water. I don't know anything about them. But injection them could be a "quick" fix, that has a chance of lasting a few weeks.

vosadrian
NSW, 456 posts
19 Dec 2025 1:55PM
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I may have located a board to use in the meantime, so I can focus on drying this board out for a repair. Funny that in general handling of the board I had not noticed it feeling particularly heavy. But in the few hours today in the sun it seems a fair bit of water has come out from the areas in front of the both front straps and the vent hole. Being a grey board, it gets pretty hot in the sun. Hopefully it will be OK. I assume I will just put it outside with a paper towel in the vent hole on a sunny day. Should I open up the cracked areas in front of the straps... either with some small drill holes or cut the outer shell off where it is soft?

I am not experienced with board repair but generally I am pretty handy with my hands. Is it worth me getting a quote from a repairer in Sydney (anyone to recommend??) or should I just have a go myself? This may also me an oportunity to put some new front strap positions which I have been wanting for years.

Muppet
WA, 107 posts
19 Dec 2025 12:19PM
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I would suggest you stop leaving the board in the sun as the UV will be further weakening your already softened board.
Having said that, I would also suggest you consider cutting your losses and putting your time, money and effort towards a replacement. An inexperienced diy repair will likely be a **** show and a pro repair is probably not worth the money on a 13 yo board that has already gone soft and been water logged. Get a professional quote and assessment then decide if it's worth it.

decrepit
WA, 12776 posts
19 Dec 2025 12:29PM
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If it's going to be fixed well, the deck should come off and damaged foam removed.
If that's the way you're going, removing the deck will allow the foam to dry out quicker.
Other wise gravity is your friend. put a wick in the lowest opening and leave in the sun.
Remove the wick after sun goes down. When wick come out dry, it should be close enough.

vosadrian
NSW, 456 posts
19 Dec 2025 4:54PM
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So for board drying, is it better out in the direct sun or covered. Obviously the direct has UV that may break down the outer shell. It is heat we are after. I can leave it in a cover or under a blanket. Probably want some air flow to dry the water coming out.

I have done some things with carbon and epoxy resins, but not as much with the foams. If I do it myself I have little to lose except materials. Anyone got a rough figure on a professional repair like this... like $200/$500/$1000?

decrepit
WA, 12776 posts
19 Dec 2025 3:24PM
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I guess a lot depends what you find when you pull the deck off.
I've seen the underneath foam destroyed for a few centimeter down, with bits floating around. This would have to be taken down to a flat surface and new foam glued in.
Other times the foam is fairly intact and the the sandwich has just detached, in that case with any luck the sandwich can just be stuck back on.
However this was bottoms blown off. your problem looks like insufficient reinforcement in front of the straps. and the foam has been depressed allowing the sandwich to flex. I doubt the foam will be in good shape.

As it's the deck, and shape isn't that important, injecting expanding foam maybe an option. but you'd need to judge quantities well.
Too little would leave a void, and too much could do more damage.

Manuel7
1324 posts
19 Dec 2025 11:01PM
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Open it up and check it out.

Otherwise, just grab any used board around the same specs because wet foam is a pain especially if wet for a while, delaminated etc.

vosadrian
NSW, 456 posts
20 Dec 2025 9:23AM
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Any details on the expanding foam thing? Is it structural enough to take my feet pounding it without collapsing? Can it be injected through a hole without opening up?

decrepit
WA, 12776 posts
20 Dec 2025 9:05AM
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There are different types, different densities, etc. the stuff in a can is fairly low density. but density will increase with compression, but too much compression could damage the board.
If injecting thru holes, that will give compression.
the 2 pack stuff has a very short working time, you have to get an even pour over the whole area quickly. then you have to get a weighted/taped cover over it for compression.
I've only used the 2 pack ones for smallish dings, not a big area.
We did use the can type on Waricles project, but I can't remember now just how we used it.

lemat
187 posts
21 Dec 2025 2:52PM
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Select to expand quote
vosadrian said..
Any details on the expanding foam thing? Is it structural enough to take my feet pounding it without collapsing? Can it be injected through a hole without opening up?


When i do it, i use to do injected hole in center of delam and smaller exhaust holes around.
I injected PU glue in centerd hole with a big syringe. Pull out syringe, close hole with plastic tape and press hard to push delam dawn, i use pieces of wood and clamps or straps, take care to let exhaust holes open, if you use enough glue, some will exhaust when you press. Let cured until the foaming pu glue exhaust is hard, dig a little each holes and close with strenghened epoxy putty. From my experiments this kind of repair can extand life of board if you don't go the big surgery repair.

berowne
NSW, 1539 posts
21 Dec 2025 7:13PM
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Repairs: www.seabreeze.com.au/forums/Windsurfing/General/Board-Repair-7
Nose Job: www.seabreeze.com.au/forums/Windsurfing/Foiling/Foil-board-Repair-Job-The-new-nose-you-all-need

kato
VIC, 3508 posts
21 Dec 2025 8:10PM
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Select to expand quote
lemat said..

vosadrian said..
Any details on the expanding foam thing? Is it structural enough to take my feet pounding it without collapsing? Can it be injected through a hole without opening up?



When i do it, i use to do injected hole in center of delam and smaller exhaust holes around.
I injected PU glue in centerd hole with a big syringe. Pull out syringe, close hole with plastic tape and press hard to push delam dawn, i use pieces of wood and clamps or straps, take care to let exhaust holes open, if you use enough glue, some will exhaust when you press. Let cured until the foaming pu glue exhaust is hard, dig a little each holes and close with strenghened epoxy putty. From my experiments this kind of repair can extand life of board if you don't go the big surgery repair.


Done repairs exactly the same way. Clamping is a must !!!!!

lemat
187 posts
21 Dec 2025 6:35PM
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Select to expand quote
kato said..

lemat said..


vosadrian said..
Any details on the expanding foam thing? Is it structural enough to take my feet pounding it without collapsing? Can it be injected through a hole without opening up?




When i do it, i use to do injected hole in center of delam and smaller exhaust holes around.
I injected PU glue in centerd hole with a big syringe. Pull out syringe, close hole with plastic tape and press hard to push delam dawn, i use pieces of wood and clamps or straps, take care to let exhaust holes open, if you use enough glue, some will exhaust when you press. Let cured until the foaming pu glue exhaust is hard, dig a little each holes and close with strenghened epoxy putty. From my experiments this kind of repair can extand life of board if you don't go the big surgery repair.



Done repairs exactly the same way. Clamping is a must !!!!!


And needed because PU glue foaming strengh reduce quickly with density and as it foam a lot without pressure if not press ended with a strenghless sponge. Exactly what we don't need here.

Paducah
2790 posts
22 Dec 2025 1:20AM
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Big delam area (basically all the area around the mast track) on old longboard. 2 lb pour foam poured onto syringe and then put plunger in. Like others suggested, filled holes with epoxy/thickner. The plungers rose as the foam expanded. You need some relief because the expansion force is not inconsequential.
98% of the time, pour foam is rhe answer vs spray foam because it has a very consistent internal consistency whereas spray foam is like swiss cheese. Just be aware of the very quick working time and wear gloves. Maybe mix a batch or two for practice beforehand.


berowne
NSW, 1539 posts
22 Dec 2025 9:06AM
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www.seabreeze.com.au/forums/Windsurfing/General/Repair-Delamination?page=1


Foam method above could cause the skin to bulge up. My method of compression caused the skin to reattach to the old foam using sand bag weights. Lazy poor man approach to vacuum which is best if you have the gear.

RumChaser
TAS, 629 posts
22 Dec 2025 1:12PM
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I've used the expanding foam (2 part) twice on the deck of boards and once on a de-lam on the bottom. On the deck, yep, quite happy with the result. The foam did push up on the deck and it bulged a bit but it was curved to start with and was hardly noticeable. However the bottom was a different result. Don't underestimate the force exerted by the foam. I weighted the bottom with some hunks of timber. No where near enough. Pumped up like a balloon. That is why I've got a nice new board to ride now!!!!!!

srtgumbee
112 posts
23 Dec 2025 9:04AM
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Link to my repair of a 2014 Isonic 87 www.seabreeze.com.au/forums/Windsurfing/General/Isonic-repair-materials--2?page=1

Lots of good advise from this forum helped me achieve a solid repair and is still super strong to this day.

Be it right or wrong, with regards to the repair in front of the front straps, I did not clamp the deck when injecting foam, but made sure there were enough exit holes for the foam to expand out of.

The major repair in front of the rear straps i cut out a slab of carbon deck entirely, then applied foam and added the slab back on with weights so foam filled in the damaged styro.

vosadrian
NSW, 456 posts
23 Dec 2025 2:28PM
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I'm still trying to dry the board out at the moment. I have another board to use in the meantime. So will try to dry the board out until no more water comes out and then I will try the expanding foam approach. How urgent depends on how I get on with the new board once the wind arrives.

In typical fashion, Sydney has gone from being very windy over the last month when I was stuck at work to no wind over the two weeks I have off over Christmas/NY.

vosadrian
NSW, 456 posts
5 Jan 2026 4:17PM
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Hi All,

I think the board is pretty dried out now. I want to try the injecting two part foam method. Can anyone suggest which foam I should use and where to get it (I am in Sydney if that helps). I checked some of the linked posts of other repairs but could not see any specific mention of the foam material used.

It looks like I want to drill a grid (30mm?) of 4mm holes over the affected area and then use 50-100mL syringes to inject the foam outer rail back towards the inner deck direction. So the obvious items I need are just the foam and syringes. I guess I will need also some UV epoxy to coat and grip the deck afterwards I'm hoping if there are enough holes close enough together the pressure should be managable to not balloon the deck too much. Also, probably want the slower (lower heat) option for the foam.

If someone can point me in the right direction for the materials I will start ordering stuff to prep to give it a go. I realise this is a dodgy fix. I just want to get the board usable for a few more years for minimum $$ and effort.

Thanks in advance!

Zed
WA, 1274 posts
6 Jan 2026 9:30AM
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Wouldn't you be better off buying a 2nd hand board. I've just picked up a as new RRD (2014) for $200. How much are you going to spend on repair materials?

vosadrian
NSW, 456 posts
6 Jan 2026 2:10PM
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Select to expand quote
Zed said..
Wouldn't you be better off buying a 2nd hand board. I've just picked up a as new RRD (2014) for $200. How much are you going to spend on repair materials?


Yes I would if could find a deal like that.... but nothing in Sydney I can see anywhere near that. And freighting boards from WA is going to add a few hundred.

I'm happy to put a few $$ into an attempted repair. I like the board. Other than the soft deck it is in excellent condition. I get to learn something in the process.

But at the moment I don;'t know which 2 part PU foam I should get... so any suggestions welcome!

philn
1058 posts
6 Jan 2026 11:47AM
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Select to expand quote
vosadrian said..

Zed said..
Wouldn't you be better off buying a 2nd hand board. I've just picked up a as new RRD (2014) for $200. How much are you going to spend on repair materials?



Yes I would if could find a deal like that.... but nothing in Sydney I can see anywhere near that. And freighting boards from WA is going to add a few hundred.

I'm happy to put a few $$ into an attempted repair. I like the board. Other than the soft deck it is in excellent condition. I get to learn something in the process.

But at the moment I don;'t know which 2 part PU foam I should get... so any suggestions welcome!


Not sure what the equivalent is in Australia, but here in the USA I use 2 pound density expanding foam.

vosadrian
NSW, 456 posts
6 Jan 2026 4:18PM
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Would this do the trick:marinetradesupplies.com.au/product/polyurethane-expanding-foam-2-part-2l-kit/

decrepit
WA, 12776 posts
6 Jan 2026 1:36PM
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Unfortuanetly that link doesn't give foam density.
the stuff inside your board could be as low as 13kg/m3 and as high as 25kg/m3
Making some assumptions here, so could be way off.
looks like 20l weighs 1kg
m3 = 1000l
so this foam is around 50kg/m3
It will add some weight, but should do the job.

vosadrian
NSW, 456 posts
6 Jan 2026 6:33PM
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Thanks Decrepit!

Not too worried about some weight. I think it would be lucky for more than 200mL to go in... and I had been probably sailing it a few sails with water ingress and it seemed fine. I never weighed it but probably took a few hundred mL of water out.

decrepit
WA, 12776 posts
6 Jan 2026 6:28PM
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Good luck with that, let us know how it goes.

vosadrian
NSW, 456 posts
7 Jan 2026 9:48AM
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Thanks decrepit!

Just one more question. In my case, I did not notice the board getting soft. My first sign was water coming out of a crack in the board when packing up. So the board had gone soft and then the outer carbon shell had been able to move and with my feet pressing the movement had caused the shell to crack and then water ingress. So the outer shell now has noticable cracks. that leak water. Will this repair technique with the PU foam seal the cracks from water ingress? My plan was to drill holes, inject the PU foam through the holes and then fill what is left of the holes with Epocy resin. So the holes will be sealed. I am just not sure of the cracks. I believe the PU foam is closed cell and should not leak if not cracked, but just checking what others think?



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"Board Repair - Soft deck crack leaking" started by vosadrian