sealing hull/liner/deck joint

[old guys sail]

Think I have determined my 26 is taking on water at this joint--the rubrail doesnt fit well in areas, I pulled most of it off and its obvious someone has done quite a but of "sealing" under there with at least two different types of sealant. There a a few areas where the joint has a crack or gap in it. I suppose rain sits on top of the rail and works its way inside the hull. Like I said, have pulled most of the rail off, want to clean both the joint and the inside of the rail, try to seal the joint, then install the rail again and then try to seal it on the top side to prevent futher entry. Any comments, and idea on what to use to seal the 58 feet or so of joint and what to use to seal the rail? Thanks

[AlaskaMan]

We used 3M 5200 and it worked great

[old guys sail]

Well, I have heard a few say 5200 should be avoided, or at the very least is for securing something that you never want to remoe again. I was thinkinking of a "paint" on type sealant.

[RobertB]

I believe 5200 is good for sealing the hull joints - but need something else to bond to the rubrail. I believe a polysulfide based adhesive is the way to go there. It is a synthetic rubber with good bonding quantities, stays flexible, and allows later disassembly.

[Ixneigh]

If I ever get to that point I'll be glassing the joint together and using a much nicer looking rubrail.

A note on my observations
The outward turned flange has little "meat" to bolt through. A few good hard dockings could crack the flange at the bolt holes and begin a process that will get worse as the boat flexes while sailed. (hard in my case)
The fiberglass is thin to thin IMHO in that area. I plan to use several 8 inch wide strips of coremat or the like to strengthen the yachts hull/ deck joint and give the upper sides of the hull more substance. I suppose I'll do that when mine starts leaking too much.
Ixneigh

[EZ]

For the rub rail to deck surfaces, recommend sealing them together with a good marine caulk. 5200 is a great product, but it doesn't seem to hold up to UV very well.