Tricky deck reinforcement

[seaangler23]

My biggest job for the winter is sorting the front deck on my mitchell sea angler 23 , over the years the fixings through the deck have allowed water to enter and rot out the wooden planks which provide the strength to the deck so it has become spongy and I can't get it to seal, the deck has a gellcoat finish that I do not want to disturb as to try replicate it to a decent standard is not worth thinking about so I will be going in from the cabin and first cutting out the fiberglass to get to the rotten planks and pull them out.
My plan is to then replace the wooden planks, from what I can see from the underside these look like around an inch thick and 12 wide so replicate these, possibly with some added strength, thinking 1" square alloy box section rolled to the same contour and placed between the planks (just an idea so far) the planks will be glued up to the deck fiberglass and once set I need to glass it in from inside which is where I an concerned as I have never glassed above my head, I can see it becoming a mess, any tips? It's a fairly large area, I plan to add a head lining so overall finish isn't a concern just strength and trying to do it without ending up with epoxy dripping everywhere

 

[prv]

I had to do a similar job with our previous boat's aft deck, though I decided to come in from above to avoid having to lay up overhead while crammed in a locker.

The basic plan seems sound, though I'm not convinced about the ally bits.

An oscillating multi-tool will be very useful for the cutting out part.

Some sort of thickened resin paste will be needed to bed the wood onto the underneath of the deck, whether that's epoxy with microfibres or polyester with short glass strands. Otherwise however carefully you trim it, you won't get the wood in 100% contact with the deck layer everywhere, leaving air gaps.

Have a bit of plastic-topped board (contiboard, old kitchen worktop, etc) to wet out sections of glass on before applying them to the job. That's how I do it on vertical surfaces. I've never tried overhead though, doesn't sound like fun

Pete

 

[pmagowan]

Just laminate in some more wood, don't bother with aluminium which will be incredibly hard to get exactly right. Remove as much of the old wood as is needed and then create a scarf for the new stuff. Use thin sheets that will easily bend to the desired shape. Coat with epoxy and put some post and wedges under to clamp in place. You can do it one sheet at a time or all together if you feel lucky. Then glass over the lot with prewetted glass.

 

[seaangler23]

Luckily access isn't a problem so an angle grinder and thin disk can cut it all out, I plan to leave a bit of glass around the edges to slot the planks in fingers crossed, I was thinking about thickening the resin but good idea with the sheeting.
Didn't think about laminating as it's only an inch but thinking about it it may be a good idea to hug the deck shape better, maby use 6mm ply, I won't bother scarfing as access to replace the lot is easy and I drilled some holes in the roof and the water has spread throughout.
Thanks, good to have to other ideas

 

[Tranona]

If the rot is extensive then remove the outer GRP deck and all the wood. Replace with either marine ply soaked in epoxy. If there is a curve to the deck it is worth scoring the ply about 50% of depth to both make it more flexible and to allow the epoxy to get well in. An alternative is to use foam as is more commonly used these days. Then relay the old outer deck. Of you make your original cut at a point where there is a change in texture, for example you can disguise the join.

There was a series of articles in PBO a few years ago describing exactly this job. Call to the back numbers office might be useful.

 

[seaangler23]

Going in from the top unfortunately isn't an option, it would require a cut across the front of the boat about 8ft wide in front if the wheelhouse, an areas where I don't want a join as it will alway flex slightly due to the size of the area, the deck has a curve so I was hoping to use the outer layer as a guide when laying the new wood which I wouldn't be able to do from the top as I am unsure how sound the bottom layer of glass is, it may come to this but I'd rather have a shot at doing it from the bottom, I have some marine ply so I may experiment with laminating when I pull it out.
Poor photos but you can see the size of the area, green tape was this years temp sealing

 

[Tranona]

Is the wood reinforcing localised or is the deck sandwich construction? If there is just a king plank and pads for the cleat bases, and if it these that are rotting then localised repairs from the top would seem the sensible approach. No need to take the whole deck (either inner or outer) unless you plan coring the whole area.

 

[30boat]

I've done it from below and believe me it's hell.If you must do it that way then cut the lower skin off and reuse it.After cleaning off the rotten core replace it with laminated plywood or hard foam glued with epoxy putty.You'll have to shore it from the underside until the epoxy goes off.Then glue the old skin back on in the same way and laminate a thin strip around the perimeter to connect itto the sides.Don't think of laminating overhead.

 

[PCUK]

I've done it from below and believe me it's hell.If you must do it that way then cut the lower skin off and reuse it.After cleaning off the rotten core replace it with laminated plywood or hard foam glued with epoxy putty.You'll have to shore it from the underside until the epoxy goes off.Then glue the old skin back on in the same way and laminate a thin strip around the perimeter to connect itto the sides.Don't think of laminating overhead.

That's the way to do it!!!

 

[seaangler23]

Good plan that man never thought to reuse it! Or il use it as a template to make a replacement It's a sandwich construction the wooden king plank is mostly cosmetic and the lower I added in an attempt to strengthen it,

 

[ex-Gladys]

Also... When refitting your deck fittings, do it the "proper" way - for a 5mm bolt, use a hole cutter to drill a 20mm hole. If you reuse the laminate underneath, stop the hole cutter before you cut the laminate. Fill the hole with thickened epoxy, and allow to cure. Drill bolt hole through the epoxy and depending on the strain on thefitting put an appropriate backing underneath... No more water ingress into the wood under the deck....

 

[30boat]

Good plan that man never thought to reuse it! Or il use it as a template to make a replacement It's a sandwich construction the wooden king plank is mostly cosmetic and the lower I added in an attempt to strengthen it,

Not my idea .Got it from an American book on how to repair fiberglass boats.

 

[seaangler23]

Also... When refitting your deck fittings, do it the "proper" way - for a 5mm bolt, use a hole cutter to drill a 20mm hole. If you reuse the laminate underneath, stop the hole cutter before you cut the laminate. Fill the hole with thickened epoxy, and allow to cure. Drill bolt hole through the epoxy and depending on the strain on thefitting put an appropriate backing underneath... No more water ingress into the wood under the deck....

Thanks for the tip, il be doing all I can to make it seal as I plan never to do it again!

 

[William_H]

Well just for some different ideas. With in effect a king plank down the centre on top I would remove that. Then cut the top layer under the king plank. Then cut around the outside edge so that you can remove the top skin in 2 pieces Port and starboard. Or one at a time. Then do your work from above.
Most non skid surfaces end about 40 or 50 mm short of the edge .The edge areas being smooth. So that wouold be an ideal point to cut. You can get a smooth repair edge fairly easy. Once the top is removed I you can cut out the rotten wood. Often balsa wood was used.
I would not use ali reinforcing. Rather lay layers of carbon fibre over the wood. Or in place of the wood. This is very stiff in itself but given enough thickness for a good geometry it can be very stiff. Polyester Foam can be used like wood to give the thickness needed for stiffness.
I think you will find it easy to rejoin the outer skin to the deck without leaks or a weak spot.
If you do choose to go from underneath. Consider using carbon fibre. ie get prices. It can be used just like glass with any resin but actually is easier to use as its inherent stiffness will mke it easier to lift up into place. Do get adjustable props ready to set up to press the lay up into place as you lay it. Use cling wrap or plastic carrier bags to stop the resin sticking to the prop. good luck olewill

 

[seaangler23]

Started pulling out the rot, a lot of rotten soggy stuff and alor of it had seperated from the fiberglass, no wonder as it's made of loads of small squares of balsa and that's end grain so it acted like a sponge

 

[30boat]

Started pulling out the rot, a lot of rotten soggy stuff and alor of it had seperated from the fiberglass, no wonder as it's made of loads of small squares of balsa and that's end grain so it acted like a sponge

That's how balsa core looks like. It's made in small squares so it can conform to shapes. I did exactly what you did and found it to be huge work. Working from above is much much easier. Anyway once evrything is dry and abraded I'd advise you to glue bits of waterproof plywood to the underdeck with epoxy putty and then reglue the old laminate back on with thickened epoxy or epoxy putty .A length of fiberglass tape and epoxy will seal de edges. I did everything with polyester because epoxy wasn't available where I was and the repair was still sound 11 years later.

 

[seaangler23]

The laminate is dead I'm afraid had to rip it off in areas I was hoping it would come off easy but no luck, it's a large area, 9 foot beam with no other reinforcement. I plan 2 layers of marine ply laminted to help with the contour then the messy job of glassing up from the underside. Going I from the too isn't an option

 

[30boat]

The laminate is dead I'm afraid had to rip it off in areas I was hoping it would come off easy but no luck, it's a large area, 9 foot beam with no other reinforcement. I plan 2 layers of marine ply laminted to help with the contour then the messy job of glassing up from the underside. Going I from the too isn't an option

Don't try laminating from the underside,it's almost impossible as the cloth will fall under it's own weigth. Instead make some 3mm fiberglass panels and cut to size . You can even place small panels side by side held by props until the epoxy kicks and then join the edges with fiberglass tape.Just make sure the polyester is well cured before gluing it with the epoxy.

 

[seaangler23]

Yeah my plan is to make the roof in sections that will fit through the door, make them with stepped so one if the pieces of ply will overlay the next section so I can epoxy them in place. When they are made il lay up the laminate on some peel ply on top of them or a template, just gives me a good idea of the size.
Then in goes the ply and epoxy in place with plenty of supports and the laminate can be held in place with screws and battons until it dries, then all the deck fittings drilled out and epoxy filled. It's a crap job but as it's a keeper it's getting done as well as possible, I'm not doing it again in 30 years

 

[NickRobinson]

Looks like a job an a half. Best wishes with it. Overhead work isn't pleasant.
Not to hijack the thread I've posted a rant-ette about balsa cores....