Fairing block material?

[ted655]

I have to install a thruhull in a fiberglass hull. Right off the start....It HAS to be a thruhull. Bedding inside is NOT an option.
I can buy factory (plastic of some type) blocks @ $65.00 apiece. Times 2, thats $130.00! There is little deadrise, so the blocks don't have to be thick. What other (cheaper) materials can I use? I have access to Cypress & White Oak. If saturated with spoxy are they suitable? What is used by others?
Thanks,

use an engineering plasic, my recommendation, can saw it, machine it, then bed it with sikaflex,

[ted655]

I buy it where? Sounds like the $65.00 stuff. I only need 2 small pieces (3" X 5")

Originally Posted by ted655

I buy it where? Sounds like the $65.00 stuff. I only need 2 small pieces (3" X 5")

geeze Ted, i,m in Australia, how would I know< look in your yellow pages and no its not expensive at all, the best stuff is green with a weave , but really I cant rememeber try G6 nylon, or as you say, any hard timber soaked in resin

[ted655]

Sorry I asked. I Googled the stuff BEFORE I replied. I found a 1,000 hits. They want to brag they make it, they want to tell me the molecular weight. They want to tell me how great it is. They want to tell me how many types they make. They want to DO everything, EXCEPT sell it!
Oh wait, 1 place in China wanted to sell me a shipping container full of it.
Auto supply stores, liquor stores & carpet cleaners are about all that are in my Yellow Pages. It's a small town.
It might be great stuff but it's scarce in a small amount, around these parts. Must be the reason they want $ 65.00 for a tiny chunk..

[alan white]

Originally Posted by ted655

I buy it where? Sounds like the $65.00 stuff. I only need 2 small pieces (3" X 5")

They use that stuff to make up jigs for shaper, router work in wood shops---available at Western Tool in your neighborhood. Or you could make a thick blank out of epoxy/cloth sandwich using scrap and squeeze the heck out of it in your vise between two stout boards covered with plastic. I'm cheap, so that's what I'd do.

[alan white]

Hahahaha! $65.00 each! I forgot to laugh.
Seems there's no end to gilding the lily! In some universe far away, there is a salesman and a boat owner who want to do it right, and both have very serious expressions on their faces as they exchange money for a fantasy, grown men discussing the question of molecular weight vs non-radio interference or what have you, of something ridiculously simple like a fairing block.

Originally Posted by ted655

Sorry I asked. I Googled the stuff BEFORE I replied. I found a 1,000 hits. They want to brag they make it, they want to tell me the molecular weight. They want to tell me how great it is. They want to tell me how many types they make. They want to DO everything, EXCEPT sell it!
Oh wait, 1 place in China wanted to sell me a shipping container full of it.
Auto supply stores, liquor stores & carpet cleaners are about all that are in my Yellow Pages. It's a small town.
It might be great stuff but it's scarce in a small amount, around these parts. Must be the reason they want $ 65.00 for a tiny chunk..

you me me larf sorry mate

[Delane]

Yeah those guys make a ton of money selling special plastic to special people with lots of "extra money" to spend on specific purpose designed items. For a small peice simply buy a plastic cutting board for K-Mart. We had the local Commissary Manager drop off tons of Bucher block cutting boards when they replaced the old. After a little planning and or sanding it was good as new and ready to shape, drill, seal and you name it. Great for backing plates as well. Cheap and last forever.

[ted655]

I knew that! (NOT!) Thanks

[alan white]

Just a word of caution regarding cutting board amterial, which I used to sell and play with when I sold commercial restaurant equipment.
Basically, this is polyethelene. Polyethelene is good for a lot of boat parts, but there's a reason it's not used much to hold bolt heads or form structural parts. It has very little ability to spring back after compession, meaning temperature cycles are effecting the shape, but any expansion compresses the material when bolted for example, and it doesn't relax competely back to its former thickness. It is like clay in this way, to an extent.
Sealant may hold it, but PE also is very slippery and that's why it's used to cover epoxy layups.
For those two reasons, i would not use PE for anything important. It might make an excellent lip on an ice box, or a "soft" pocket in the sole for anchoring a companionway ladder. All fine. But having worked with it for years, I would not trust it for something like the use in question.
The suggestion to clamp scrap glass in an epoxy sandwich in the vise between two flat surfaces will cost maybe five dollars each, and the resuting block will be easily machined on woodworking tools. Sealant will stick well to it, it will not expand or contract in any meaningful way, and it will not deform to any great degree when fasteners are tightened.
Many parts could be made this way such as would angle cleats or shim engines and bearing mounts.
Compessing in a vise ensures a very high glass to resin ratio with very high saturation, and another advantage is that mounting studs can be formed in situ so that no filling is required outside.