Sealing Seams (again)

[vtsnipe]

Yup, I've read all the horrors of 5200, and debates on this subject ... but it seems everyone assumes that the boat being sealed is a 42' whatever which sits in the water all season. I'm no expert, no preconceived ideas, and little experience. I think that with a small (15.5') wooden boat with cotton and putty that is trailered, that I will be taking on water every time I "dip it"?

What would you all recommend for such a boat, dry-sailed? Thanks in advance.
Chris

[Ken Hutchins]

OK, I'll jump right in and get everybody excited and phissed off. Properly caulked with cotton, then what to use for a paying compound? Any of the putty types of paying compounds will crack due to the limited elogation of the putty type paying compounds, this cracking will leave a nice place for the water to enter your boat until it swells up, not good for a trailered boat.
Now 3M 5200 will elongate 1350% this will allow for the expansion and contraction of the wood without failure of the paying compound.
The seams must have the cotton, not just the 5200. This gives a wider gap for the paying compound, to permit the 1350% to work to full benefit.
The 5200 should be applied to bare wood for proper adhesion, otherwise if the seams are painted you are relying on the paint to maintain adhesion.
In his book "Details of Classic Boat Construction" Larry Pardy recommends using 5200. Well this past winter Larry was in Mystic and I went there to meet him so I could ask him in person specfically about using the 5200.

I asked him "Larry, in your book you recommend using 5200 as a paying compound, Now tell me honestly would you use 5200 on another boat."

He replied, "Absolutely, it is far superior to anything else available." I followed up with questions about repairs, no problem, an exacto knife along each side of the seam for removal. He did emphasize, got to use the cotton, don't use just the 5200.

[Gary E]

I have used 3M5200 that way since the mid 70's or so, and untill a better material is found I will continue using it that way. Larry know whats good, agree with him 100%.

There is no reason that your dry sailed...how you do that? ina grass field? anyway, dip the boat in the water, toss it in the water, drag it into the water and you'l be just fine.

[ 07-30-2004, 08:44 PM: Message edited by: Gary E ]

[TomHaven12]

Ken, Are you talking about new construction or re-caulking an older boat, or both. Specifically, what would you recommend for a Haven 12 1/2 now under construction; carvel planked with Atlantic White Cedar? Most of the builders I know are using 3 or 4 threads of cotton, red lead paint in the seams, and then Sikaflex 291.

Are you saying cotton and 3M 5200 would be better? On bare wood seams (no paint)? Why not 3M 4200?

[Ken Hutchins]

Both, here is why:
...........................4200...........5200
Tensile strength..300.............700...PSI
elongation...........900%........1350%

I guess 4200 could be used, but IMO if you are going to spend the time why not use the stronger, permanent material. Also 5200 is listed as a permanent bond and 4200 is listed as general purpose.

[Bob Smalser]

I use a poly sealant that's a 5200 equivalent. It lasts.

But I make sure the wood is coated thoroughly with paint, first. That way it comes off with difficulty but at the expense of the paint and not the wood.

But I don't own a boat over 14' long, so I can tolerate pains I probably wouldn't with a boat 40 feet long.

[ 08-04-2004, 12:19 AM: Message edited by: Bob Smalser ]

[S/V Laura Ellen]

After reading the posts on filling seams, I have opted to use Interlux seam compound on my 37' 1937 Bluenose Junior Gaff schooner. The idea of getting 5200 out of seams to do future planking repairs sold me on the use of the traditional seam compound.

I had a great deal of problems tracking down seam compound, Interlux does not market #30 or #31 seam compound in Canada (I heard due to product labling issues). I will have to get it from a US dealer.

If anyone has any pearls of wisdom on applying the seam compound I'd be interested in hearing.

Allan

[Mike B]

Bob,

I was preparing to install a newly built transom on my 13' drifter. The new transom was fabricated from 3/4" ply, with interior edges reinforced with an additional 3" wide 3/4" ply along all four edges.

I am coating it with epoxy (System Three), and had planned to bed it into 5200 when installed...but, if I understand you correctly, you would first paint all the edges and surfaces it would contact and be secured to, then lay down the 5200 to bed it into? (Had planned to paint after finishing the rest of the interior).

Mike

[Bob Smalser]

I was talking about seams where the cotton or oakum will have to be replaced eventually.

Transoms are more permanent, and I wouldn't hesitate to bed it in poly....my solid transoms are.