Dent in my plywood hull! Help please

[Harveyfh]

I’m new to boats, and my anchor which I only just got, I stupidly put in the foredeck, which didn’t have any protection between it and the plywood hull.
Although I’m sure I was gentle putting it in, there is now a dent that is showing light from the other side. Essentially a small hole in the boat.
What should I do?
Any help + tips appreciated thanks!
Edit btw this is below the waterline!

 

[Hacker]

Number of ways to do it ranging from cutting out the damaged area to a fibreglass repair. Most important issue is to stop any water getting into the ply core, it will track and cause extensive rot. You don’t say what the deck is finished with. If it is glass then that’s the way to go. If not it really would depend on how you want the finish to look.

 

[Minerva]

Looks like you need to cut out a larger square out around the damaged ply, then scarf in a new piece of ply. Ensuring a good overlapping joint. Probably want to put a backing piece of ply on the underside too to hold it in place / ensure a good joint.

If however it failed with as little encouragement as you suggested, then it may sadly be indicative of the condition of the rest of the ply....!

 

[Harveyfh]

Number of ways to do it ranging from cutting out the damaged area to a fibreglass repair. Most important issue is to stop any water getting into the ply core, it will track and cause extensive rot. You don’t say what the deck is finished with. If it is glass then that’s the way to go. If not it really would depend on how you want the finish to look.

I’m not bothered greatly about aesthetics, and I don’t really fancy cutting out pieces of the boat, as I’m new to boats and never repaired one before.
What do you mean by the deck finish?
I think it’s marine ply and paint on the inside and marine grade paint on the out.
I would preferably do a fibreglass
Reckon it would be a sand flat and get some of the paint off, then resin, then glass, resin, glass, resin, glass, etc?

 

[Hacker]

If it’s paint finish inside and out then it needs something additional. You could strip back the paint on both sides and do a fibreglass repair but you will end up with some form of a lump (not an issue inside but would be obvious on the outside). The better option is as @Minerva proposed. Cut out a square (can be other shapes but this is likely to be the best) that removes the damaged area. You then need to put a scarf on all 4 sides (from the outside) that is at least a 1:6 ratio. Make a filler (graving) piece that is scarfed to the same sizes. After a check fit you should ideally epoxy it with clear then thickened epoxy. Put in place then add weights whilst it goes off. I’d probably epoxy a backing pad underneath. That would be the optimal repair which would allow you to repaint the deck. For a lesser quality repair you could replace the epoxy with something waterproof like Collano semperco. For an even lesser quality you could use a waterproof external glue.

 

[Harveyfh]

If it’s paint finish inside and out then it needs something additional. You could strip back the paint on both sides and do a fibreglass repair but you will end up with some form of a lump (not an issue inside but would be obvious on the outside). The better option is as @Minerva proposed. Cut out a square (can be other shapes but this is likely to be the best) that removes the damaged area. You then need to put a scarf on all 4 sides (from the outside) that is at least a 1:6 ratio. Make a filler (graving) piece that is scarfed to the same sizes. After a check fit you should ideally epoxy it with clear then thickened epoxy. Put in place then add weights whilst it goes off. I’d probably epoxy a backing pad underneath. That would be the optimal repair which would allow you to repaint the deck. For a lesser quality repair you could replace the epoxy with something waterproof like Collano semperco. For an even lesser quality you could use a waterproof external glue.

Should be ok with a lump as it will be submerged! Should I use a thickened resin or just normal like in any fibreglass kit. Thanks for your help!

 

[Minerva]

Should be ok with a lump as it will be submerged! Should I use a thickened resin or just normal like in any fibreglass kit. Thanks for your help!

By submerged - do you mean below the waterline?

If so you really do not want to bodge that!!

 

[oldbloke]

The previous posters have given v good advice, however, the easy bodge is to remove or wiggle back into place the protruding piece screw and epoxy a bit of plywood underneath, then fill the dent with with a sloppy epoxy resin / filler mix. You don't need an expensive filler , flour or talc will do. Then paint. Will still be good when the rest of the boat rots away. 30 minutes max

 

[Daydream believer]

Will still be good when the rest of the boat rots away. 30 minutes max

I think that the boat will last longer than that

 

[Harveyfh]

Looks like you need to cut out a larger square out around the damaged ply, then scarf in a new piece of ply. Ensuring a good overlapping joint. Probably want to put a backing piece of ply on the underside too to hold it in place / ensure a good joint.

If however it failed with as little encouragement as you suggested, then it may sadly be indicative of the condition of the rest of the ply....!

I must have knocked the anchor without realising it. I’d like to think the boat isn’t

By submerged - do you mean below the waterline?

If so you really do not want to bodge that!!

yep. Any tips? My first time fibreglassing!

 

[Hacker]

If using epoxy on bare wood you always use normal first (so that the wood can absorb some) before you use thickened. If you just go in with thickened at the beginning you run a risk that the wood absorbs it without it actually acting as a glue. Just mix some resin/hardner in a cup, paint some neat to both surfaces and then put thickener of choice into what’s left, apply that to one surface and then press surfaces together with appropriate weights or clamps. Use parcel tape on these so that they don’t stick. You want to see some squeeze out so that you know the joint isn’t starved.

 

[Harveyfh]

If using epoxy on bare wood you always use normal first (so that the wood can absorb some) before you use thickened. If you just go in with thickened at the beginning you run a risk that the wood absorbs it without it actually acting as a glue. Just mix some resin/hardner in a cup, paint some neat to both surfaces and then put thickener of choice into what’s left, apply that to one surface and then press surfaces together with appropriate weights or clamps. Use parcel tape on these so that they don’t stick. You want to see some squeeze out so that you know the joint isn’t starved.

In regards to the fact that I’m a newbie to boats and fibreglass, is this fix easy? Im considering getting some professional support with, but don’t know who to contact/ I don’t want it to cost me an arm and a leg
So do I apply a clamp even if I don’t want to patch over with plywood, but rather just a patch of fibreglass?

 

[Tranona]

My concern is why did just dropping an anchor make such a big hole. Either the anchor is very heavy or the ply very thin (or rotten!). anyway as the panel looks flat the easiest way to repair it is to remove all the paint from the inside back about6" from the edges of the cracks, cut out the damaged bit to leave a neat square hole. Epoxy a 6mm ply doubler inside using screws to hold in place. Make a patch for the hole om the outside using the same thickness ply as the hull and epoxy/screw that in place. Fill and fair with epoxy fairing filler then paint.

 

[oldbloke]

All of these proposed fixes are easy, one of the great things about epoxy resin is that it fills the gaps with something stronger than the original so accuracy, whilst aesthetically pleasing,isn't vital. While you could just fill the dent with car body filler or somesuch the concern is that the piece has been , or was already, weakened. Hence the suggestions of either removing and replacing the area or reinforcing from below. "Fibreglass" being thin won't do much reinforcing even though it is quite strong.
The ordinary "fibreglass" uses a polyester resin which does stick to other things very well, you need an epoxy resin which is much better. So forget Halfords and use a chandlery or an composite specialist

 

[38mess]

Easiest way is to knock the wood back into place and clean it all up and epoxy a ply patch either side, glued and screwed. Painted up. How did the anchor knock a hole in the ply?

 

[Fr J Hackett]

What would I do? Not being familiar with Woden boats but a reasonably accomplished wood butcherer, I would rout out on the outside a patch an oversize hole about 1/3rd depth of the original ply then glue in with epoxy a matching piece of stepped marine ply as a plug then do the same from the inside. Any surface imperfections can then be filled and faired with thickened epoxy or fairing compound and sanded back then painted.

 

[Wansworth]

Woden was a Viking god

What would I do? Not being familiar with Woden boats but a reasonably accomplished wood butcherer, I would rout out on the outside a patch an oversize hole about 1/3rd depth of the original ply then glue in with epoxy a matching piece of stepped marine ply as a plug then do the same from the inside. Any surface imperfections can then be filled and faired with thickened epoxy or fairing compound and sanded back then painted.

 

[Fr J Hackett]

Woden was a Viking god

Yes I repaired his boat as well

 

[srm]

Yes I repaired his boat as well

Which was best, linen fibres or wool, for reinforcing the tar?

 

[Wansworth]

Which was best, linen fibres or wool, for reinforcing the tar?

Don’t think Woden would have given the time of dayto thin ply