Vinylester & Epoxy question

[JohnV8r]

Guys,

My new rudder shelf and new forward cockpit bulkhead are made of Coosa Bluewater 26. The rudder shelf is two 3/4” Coosa sheets with woven roving between the sheets. I have routed the edges and basically followed all of Capt. Patrick’s rudder shelf design elements in the building tips section. I’m at the point now where I’m going to lay up the 1708 on the outer skin of both the rudder shelf and forward cockpit bulkhead.

I would prefer to use vinylester to lay up the outer layer of 1708 on both pieces because of the faster cure time and cost. I will glass the pieces to the hull and/or stringers at the appropriate points with EPOXY resin, not vinylester. I have always been told that you can use epoxy resin to glass in a vinylester piece. However, this is the first time I would be glassing in a vinylester finished STRUCTURAL piece to a hull with epoxy resin.

I want to confirm before I finish the rudder shelf and bulkhead with 1708/vinylester that there is no issue glassing them in with epoxy resin. Will someone please let me know if I am correct that I can glass in the vinylester finished structural pieces with epoxy without fear of delamination issues down the line?

Thanks in advance!

[JohnV8r]

BTW, the rudder shelf will only be glassed in on the outer ends per Capt. Patrick’s instructions. They will be through bolted to the inner stringers per his plans. The bulkhead will only be glassed in.

[Tony Meola]

John

I have been told that vinylester does not adhere well to cured epoxy.

I know everyone says Epoxy only for repairs but I used to know a glass guy who was one of the crew from Henriques. He was one of the Main glass guys at one time. He told me that if you know what you are doing and are careful, that vinylester works just as well as epoxy for repairs.

[IRGuy]

I believe epoxies will bond to vinylester but vinylester will not bond to epoxies.

[JohnV8r]

Perfect! That's what I thought.

[RAWicklund]

Your using 2-3/4" coosa boards for the shelf....1.5" total thickness? Too thick, or am I missing something?
Ray

[Yannis]

Mine are 4 cm thick solid mahogany plasticized with 3 layers, plus they are interconnected with a 0.5 cm thick stainless steel surface which is through bolted on both ends...
The guy who did it was an Olympic gold medalist in sailing and obviously has seen a lot in his life.
I had no reason to disagree.

[Rawleigh]

Epoxy is an adhesive and will stick to vinylester .

[JohnV8r]

Ray,

The top of the rudder shelf will be the same height as the original rudder shelf. On my 1978 FBC, all the critical fittings (flange bearing and locking collar) were the top of the rudder shelf.

I never considered that a total rudder shelf thickness of 1-5/8" would be too thick given that the composite build in the Building Tips sections is 3 layers of 3/8" composite coring material with two layers of 24 oz roving and the top & bottom covered with 1708. I figured each layer of glass in the composite build would add at least 1/4" total (1/16" x 4) to the thickness of the 1-1/8" thickness of the core material. Total overall thickness of 1-3/8" versus 1-5/8" on mine.

It's possible the tops of the bolts in the compression fitting on the top of the rudder port could be a little tall, but those could be shortened slightly if necessary. I'll know in a couple of weeks. If I am too thick and can't shorten the bolts, I'll just route out a net 1/4" I guess. That would be a major PITA!

[RAWicklund]

John,
I doubt you'll have any problems. I went and looked at mine this morning to figure out why that would be too thick for me. I used two pieces of 1/2" core cell when I did mine a few years ago on my B28 .
I had to do a lot of the work/assembly in place due to my fuel tank being in the way .Which is different from the 31 and other 28s . So I wasn't able to fit the whole assembly thru the hatch.

My rudder is recessed 1/8" in my flange Bering due to the height of my shelf..........so if I was any thicker I would have been screwed. But where I strayed from the original plan is that I set the shelf on top of the outboard stringer due to not being able to make a strong corner connection. I did glass in a 2" strip of the core cell on the fwd edge for additional strength so mine is 1.5" thick just in front.I also put a vertical piece of 2 ply core cell, bolted to the outboard stinger like in Capt.Pats tutorial, but it was messy since I had to do that in place and not the strongest connection.

So when you said you were building yours 1.5" inches thick it raised a flag to me.

Ray

[Snipe]

John I built mine out of two 3/4in pieces of Coosa as well. My measurements say it will be fine with two inches to spare. I will be glassing it in this week. One day I will figure out how to post pictures on here. I used west system on everything.