Interior work/Mast compression prevention

[sizertl]

Howdy!
I've gutted the interior of my sailboat and It's almost ready to paint. Before we paint we are reinforcing the bulkhead under the mast (there no signs of compression yet/we just unstepped the mast), next we are closing up the bottom half of the companionway, and right before painting we are going to apply a resin over the fiberglass to hide the honeycomb look.

A few questions.

1. What's the best way to reinforce the athwartship Bulkhead. Our goal is to strengthen the mast without putting a post in (it won't fit).

2. What type of resin do you recommend that will bind to fiberglass, be okay to use for closing up the companionway, and will provide a good base to paint over? Or Should we fiberglass for structure and then apply resin?

This is for my 1981 Lancer 28. It's in great condition, but it's my first big project and I can use all the advice I can get!

 

[sizertl]

Also- What are y'all's thoughts on using fiberglass for the purpose of strengthening (the hull itself, the hardware holding the chainplates, and the area surrounding the mast both in the cabin and on the deck). What thickness cloth should I use?

 

[Charlie Jones s/v Tehani]

I found your note on the boat.. Have not had any free time, but will give you a call today. Sorry about being so slow.

 

[sizertl]

I appreciate it! No rush!

 

[CarlN]

It's great you're fixing an old boat. But it's usually best to stay with the builder's original plans. Making changes can cause all sorts of unforeseen issues.

It's very hard to do a neat job in fiberglass without a mold. You are likely to really lower the boat's value. Putting in reinforcement could actually cause trouble in drainage or making hard spots where the hull is designed to flex. There are lots of 50 year old fiberglass boats sailing around without added reinforcement.

For the mast - why do you think it needs reinforcement? Is there any deflection now? Any rot? Again, if nothing has happened in 30 years it's not going to happen now - unless there's rot in the deck core, obvious cracks or major deflection. And a reinforcing the bulkhead won't help a deck core problem. I'd drill a couple of 1/8" holes near the mast step and see if there's any dampness. If so, come back for help. If not, the mast should be fine.

For the companionway - Why do you want to fill in the companionway with fiberglass? It will be a pain in the neck at dock or anchor. Just make some new hatch boards - varnished mahogany will look great. Keep the lower board in when sailing for safety. Make some cloth bags to keep them in when stored so they don't scratch. If you don't want wood, make them out of Starboard plastic board.

For the texture - If you try to fill the texture, any remaining depressions or high spots will be more obvious. The texture is likely to look better. I'd just paint it. If there are already problem areas then get an epoxy fairing compound (You can add micro ballons to West epoxy or System III makes one already mixed.). It goes on like butter and sands easily.

Be careful with resin near chainplates and hardware. Stainless steel can corrode if it is not exposed to air (called crevice corrosion). If you haven't already, remove the chain plates to check them and the bolts for crevice corrosion. I've never known anyone who's lost a mast from deck compression but plenty from bad chainplates and shrouds due to corrosion.

For hull strengthening, is any fiberglass cracked or peeling - especially any "tabbing" between parts of the boat? If "yes", come back for help with pictures. If no, it doesn't need reinforcing.

Good luck

 

[sizertl]

Wow-Thank you, I appreciate any advice that has me doing less work! Much appreciated.

 

[Charlie Jones s/v Tehani]

I appreciate it! No rush!

Was at marina a good while yesterday. Sorry I missed you. We'll try again

 

[CloudDiver]

Lancer Cabin Pics

I don't know what year your Lancer is, so I can't determine if a compression post was in the original design or not. I found examples of both with and without compression posts, pics included.
It appears that the addition of a compression post may have been an owner modification. Its not uncommon that the original design of a boat is later deemed inadequate under certain circumstances, in this case it seems like the shroud tension put too much compression on the cabin roof. It the more clear pictures is an example I found where there is a compression post that appears to be sanded carbon fiber, it could be plain old carbon steel also. More importantly the yellow arrow points to a reinforcement arch of hardwood with knees that are sistered to the bulkhead. That may have been original design, may not be. If I wanted to strengthen the cabin roof that's what I would do, but I would also want the compression post. My only concern about this example is where the compression post foot is on the cabin sole (2nd pic). What is under that? Isn't that where your keel bolts are?

 

[CloudDiver]

Not a great pic, but I found this shot of a Lancer 28 without a compression post. it also appears that there is no hardwood arch & knees on the athwartships bulkhead.

 

[CloudDiver]

I am assuming that bulkhead is 3/4 inch. If it were only 1/2 inch that would raise an eyebrow. I'd also have to be familiar with how the cabin top fiberglass laminates are laid to get an idea of strength, though I am no engineer. Simple logic says that this mod has obviously been done by others so there must be some good reason for it, as I said before probably too much flexing from shroud tension and additional forces when actually sailing.
Its conceivable that you could double up the entire bulkhead, but I think that would be way too much work to achieve the same result as above pictured wood arch and knees. An OCD nutjob like myself would CNC plasma two arches of 3/16" Stainless, one for either side and through bolt them, sandwiching the bulkhead. I have the tools to do that, I do realize that most people don't...
The compression post example above is well behind where the mast actually sits on the cabin top, but it is the most sensible place to put it and helps equalize compression with the arch. I'd be concerned about how the top plate and foot plate are attached and what is under them. If they are solid/structural points, good to go. I mentioned before I was worried about what is under the foot plate (keel bolts?), but also there could be a void behind the overhead finish material.

To answer your previous question, use epoxy... polyester resin doesn't have the greatest secondary bond strength. Then again, I'd go with what Carlf said above, don't fill the companionway at all. I am assuming you want to filler the lower 3 or 4 inches because a nasty wave can fill the cockpit, overwhelm the cockpit scuppers, and then flood into the cabin... Why do a messy job that may not look right when you can just leave the lower crib-board in place on nasty days?