Mast base flange. How to fit deck curvature?

[Chotu]

I am finishing up the design of my mast base right now.

It is not very easy or accurate to have the fabricator build a curvature into the mast base itself.

Instead, I would like to use some kind of deck plate below the mast base to account for the slight curvature. It’s maybe 1/4 of an inch of curvature. Similar to installing a deck hatch.

My question is, what material should I use for this deck plate?

Wood seems easy, but of course that is the worst thing you could use since it will rot. not a good place to have things rotting away. I have been using PVC plastic for deck hatches, but, I think that is too weak. It is kind of soft. It will probably crush under the forces of the rigging.

[fourlyons]

You could laminate a pad in place, using polyester resin of course. Build it up with layers of 1708. Then flatten with high density filler, then one more layer of 1708 to reenforce the surface of the filler. Then fill, sand, and paint. If you're only talking 1/4" of camber, and don't need to spread the load out, it wouldn't need to be very thick.

[Chotu]

Originally Posted by fourlyons

You could laminate a pad in place, using polyester resin of course. Build it up with layers of 1708. Then flatten with high density filler, then one more layer of 1708 to reenforce the surface of the filler. Then fill, sand, and paint. If you're only talking 1/4" of camber, and don't need to spread the load out, it wouldn't need to be very thick.

Thank you. I appreciate the response, but the amount of hours of work involved is way outside what I have time for. I just need a flat piece of sheet material that I can take a grinder and a router to and shape and then stick in place and drill holes for the through bolting. Something with decent compression strength.

And the less hazardous chemicals I use the much better life is. I have been reacting strongly to nearly everything. Resins are problematic for me entirely now.

PVC sheets are perfect for hatches. I just need something that’s not going to squish under the load of the rigging. And that won’t rot.

[fourlyons]

How about phenolic sheet? I realize it is a chemical, but even pvc is a chemical.

[Chotu]

Originally Posted by fourlyons

How about phenolic sheet? I realize it is a chemical, but even pvc is a chemical.

Sorry. I should be more clear. Resins are the problem. When they are still separated into their components.

All plastics are OK once they are hardened. Except epoxy.

So any kind of man-made sheet that won’t rot will work out. As long as it can stand up to a mast pressing down on it.

I am looking at a sheet about 28 x 28 and 1/2 inch thick max.

I was good with polyester for a while, but it started affecting me also. It was causing my sinuses to bleed profusely.

[fourlyons]

Sorry, I missed the issues with all resins. Are you sure PVC wouldn't work if your fabricator welded a plate to the bottom of the mast extension to spread the load?

[Rumrace]

PA12 nylon with Kevlar laminate. Or PA6 with Polycarbonate. Both are everything proof lightweight
They both solve nylons UV and warping issues. ASA would also work and stands up to UV fuel chemicals.
Polyester nope. The epoxy family again CF or PC adders or nope

[Rumrace]

28x 28x1/2 is close enough to a kilo. Pa6 my pick it’s $73.00 a kilo

[Chotu]

Originally Posted by fourlyons

Sorry, I missed the issues with all resins. Are you sure PVC wouldn't work if your fabricator welded a plate to the bottom of the mast extension to spread the load?

I would absolutely love to use PVC. I already have a piece ready to go onboard. Actually, no. Wait a second. I think the hurricane destroyed it. But still. It’s at Home Depot in 4 x 8 sheets. Half inch thick.

If it could take the compression of the mast, spread out to a 24”x24” surface, The thread is solved.

[Chotu]

Originally Posted by Rumrace

28x 28x1/2 is close enough to a kilo. Pa6 my pick it’s $73.00 a kilo

Any chance you can provide a source? Just for comparison? I just looked it up and it looks like some bearing grade material and it was more than $1000 for the piece I’m looking for.

[Cheechako]

Originally Posted by Chotu

Thank you. I appreciate the response, but the amount of hours of work involved is way outside what I have time for. I just need a flat piece of sheet material that I can take a grinder and a router to and shape and then stick in place and drill holes for the through bolting. Something with decent compression strength.

And the less hazardous chemicals I use the much better life is. I have been reacting strongly to nearly everything. Resins are problematic for me entirely now.

PVC sheets are perfect for hatches. I just need something that’s not going to squish under the load of the rigging. And that won’t rot.

-Wood is a bad choice as it cracks readily in that situation.
- Obviously you haven't worked alot with metal, that idea will take forever and many $ worth of grinding materials. Milling it would be done but NO not simple or cheap.
-You could grind or mill various plastic materials by hand grinding and fitting as you go using a radius gage.
-There's really not enough compressive force to squish it. If the pad is say 6" x 10" and there is 600 lbs of compressive force you are only at 10# per square inch. The material is probably good for many times that compressive force.
-But really, the suggestion to laminate it the way to go I think. You can tape down wax paper on the deck or buy wax sheets which used to be readily available and laminate the shape over it. Maybe you can get someone to laminate it for you?

[Chotu]

Originally Posted by Cheechako

-Wood is a bad choice as it cracks readily in that situation.
- Obviously you haven't worked alot with metal, that idea will take forever and many $ worth of grinding materials. Milling it would be done but NO not simple or cheap.
-You could grind or mill various plastic materials by hand grinding and fitting as you go using a radius gage.
-There's really not enough compressive force to squish it. If the pad is say 6" x 10" and there is 600 lbs of compressive force you are only at 10# per square inch. The material is probably good for many times that compressive force.
-But really, the suggestion to laminate it the way to go I think. You can tape down wax paper on the deck or buy wax sheets which used to be readily available and laminate the shape over it. Maybe you can get someone to laminate it for you?

OK. Cool. If PVC works, like the kind you can get at Home Depot in the 4 x 8 sheets, I will probably just use that. I have been using it with great success for this type of trim ring application all over the place. Just nothing with a big load on it, so I was concerned.

As far as laminating being the way to go, I have to ask. Why? It’s just some dummy block in compression. Why would you want to laminate something that is just in compression?

[rslifkin]

Originally Posted by Chotu

As far as laminating being the way to go, I have to ask. Why? It’s just some dummy block in compression. Why would you want to laminate something that is just in compression?

I'd think just for ease of getting the shape perfect, as you can build it against the deck as a shape template (vs cutting to shape, test fit, adjust if needed, etc.)

[Rumrace]

It’s a good question which I’ve asked. Laminates apparently are not there for compression but sheer strength. The poly carb or carbon fibre infused in various polymers give it connected strength so the centre weight wont cause swelling and cracking around it. Stabilizes surface tension or similar wording. The DuPont guys make my eyes glaze over with plastic knowledge. I have less than 3 kilos of PA6 we don’t use much. I get mine from Netherlands. While the pa6 is not a laminate it’s not the plastic equal of press board. The carbon fibre links up with full length connections. Starts in the cure as a chopped fibre. Depending on the blend it has crazy compression strength. So pa6 is a laminate at a cell level

[Cheechako]

Originally Posted by Chotu

OK. Cool. If PVC works, like the kind you can get at Home Depot in the 4 x 8 sheets, I will probably just use that. I have been using it with great success for this type of trim ring application all over the place. Just nothing with a big load on it, so I was concerned.

As far as laminating being the way to go, I have to ask. Why? It’s just some dummy block in compression. Why would you want to laminate something that is just in compression?

really just because it's an easy way to get a close intimate fit. But heck, just put it on there with some 5200 to fill any imperfections!
Not a big fan of PVC for most anything, but there are plenty of high strenth type things out there.