3M 5200 vs. 3M4200 for bottom seams

[Bill Morgan]

My 1962 Chris Craft 20' Holiday was transported from PA to CA. It's had over a year for the planks to dry out. Now the gaps between the planks are +/- 1/4 inch. I have sanded all the anti-fouling paint off to bare wood, cleaned out the old caulking and ready to go. I will be using the Smith sealer and epoxy system..then finally..the hard racing paint. The previous owner used the run-the-water in the bilge for days until the bottom swells and the seams stop leaking. This seems like it would put a lot of stress on the bottom...especially if you had to do this everytime you wanted to take the boat out. The question is...which is best to use to fill the seams...5200 or 4200?? The boat mainly will be in the water for a day then back on the trailer till the next time. I would really appreciate hearing from you and any advice/experiences. Thank you. P.S. The bottom, after 40 years, appears to be very solid. This is a 50 MPH boat...probably 20 MPH would be more reasonable smile.gif hate to see those planks trailing behind me smile.gif

[High C]

A 5200 footnote, if you ever want to go back and remove or replace any of those planks, you can pretty much forget it if they've been glued with 5200. The stuff is very permanent, and very difficult to remove. It's easy to damage adjacent planks and frames when trying to cut out 5200.

If this were an "in the water boat" I'd be able to offer a bit more help on how to proceed, but a wooden trailer boat has its own unique problems with repeated dry/wet cycling of trailering. Others here will surely offer their expertise.

Good luck (and put away that 5200 ;) )

[ 10-03-2003, 12:47 PM: Message edited by: High C ]

[Bill Morgan]

Looking up at the seams (1/4" X 1/4") between the 5" wide mahogany planks I see the second X bottom which the planks are attatched to. What you are suggesting is...do not let the 3M seam compound come in contact with the second bottom by placing a strip/tape inside each seam. Result: only the edges of the planks will be in contact with the 3M ..so any expansion or contraction will have the freedom to move free from the second bottom. Thank you for your advice.

[Dan McCosh]

All of my experience is with hulls that stay in the water, but I think that a day in the water after the hull is dried out won't actually begin the swelling process. The adhesion of 5200 is strong, but it's not a great seam compound. I'd recommend a polysulfide with the appropriate primer, which should do a good job and not lead to the problems mentioned above. It stays flexible, takes compression well compared to 5200, and is pretty much the standard. Your double-planked bottom originally had a layer of sealant and cloth betwen the layers, and was supposed to allow this kind of action. Probably gone now, but it still would slow leaks when the boat is first launched.

[holzbt]

Before you do anything else go and buy a copy of "How To Restore Your Wooden Runabout" by Don Danenberg. I cannot recommend this book highly enough and it deals explicitly with these types of boats and their common problems (Like huge seams).

[Bob Adams]

Bill, please do not use those products in your seams. Polyurethane is too tough for that application. When the wood swells, you will cup every plank in her as the compound refuses to yield to the expanding wood.Polysufide would be a much better choice.

[Bill Morgan]

First, I want to thank you all for taking the time to respond to my questions. I found the following polysulfide products:

1. GS1-301 HULL CAULK by Detco
2. Black Boatlife 2-part Life Caulk-Fast curing polysulfide deck & hull seam compound.

I checked with Smith & Co. and they no longer carry or produce this caulking.

Any suggestions on which product would be better to use? and do I still need to tape the inner part of the seam to keep the caulking away from the second bottom? or just fill the seam and not worry about it?

[holzbt]

READ DANENBERG'S BOOK BEFORE DOING ANYTHING TO YOUR BOAT! Sorry to shout but please read this book before you put anything in those seams that you might regret later on.

[cdm4]

Bill, The problem with putting any kind of caulk in those seams is that when the planks swell, and sooner or later they will, the planks will rip your frames apart. You really could sink your boat this way. The bottom was designed to have a tight fit between these planks. Also there should be a layer of fabric between the two bottom layers that was soaked in basically heavy paint to act as a sealer. If you can see the seams of the inner bottom, then this has rotted away. Not trying to tell you what to do but you really should use the boat as is our have it restored. CM

[Dale Genther]

I second holzbt's suggestion. GET & READ the book BEFORE doing anything. I have a 1952 22 ft. Chris Craft Sportsman, which is probably the same construction as your boat. These boats have some unique characteristics which you had better be aware of.

[ 10-06-2003, 11:28 AM: Message edited by: Dale Genther ]

[JFH]

If this is a carvel planked boat and you want the seams to close...you simply must leave her in the water. Preferably using a sling in a boathouse for a week or two and then use the boat as it was designed for. Making a trailer-friendly version of this craft would involve removing all the bottom planking, replacing it with the appropriate marine-grade plywood and sealing all with Epoxy Sealer. This is the only real way to do this properly. Caulking the seams with a more flexable caulking like 3m 4100 is ok if you like bulging seams after she soaks up. I would not recommend the 5200 for reasons already stated.

If the boat is never going to be allowed to soak up and you are not too afraid of bulging seams and a real bitch of a time reefing out the stuff someday....then go for it and enjoy her for a few years. Otherwise..., have the bottom epoxified and never have to worry about seams at all.

Just my two cents worth.

Jim

[Bill Morgan]

Great advice! I'm just glad that I have had so much help/advice from all you guys. When the boat arrived from PA the seams on the bottom were slightly over 1/8"....now they are 1/4". When you look at them straight on they look awfull wide to caulk. Again, because of my geography, I don't have anywhere I can leave the boat in the water as you would back east. With the Smith system, the bottom and seams would be sealed with clear penetrating epoxy sealer..then painted with thier epoxy paint..then the hard racing paint by Pettit Old Salem.

If the boat is in the water for no more that 5-6 hours then on to the trailer...would this be enough time to affect the bottom and make the polysulfide start bulging?

I do see the cloth.. except for where I cleaned out the seams. It sounds like it would be a good idea the mask the second bottom from the caulking ..which should only contact the planks.

Unfortunately, we don't have all the restoration shops you have back East. They could look at this bottom and tell me whether I'm crazy or not and have the bottom redone. The planks are 95% in beautiful shape..except there are a few they have crack/and deep groove marks where it looks like the previous owners ran over a rock. I was planning on grinding these clean and use the Fill-it product..then seal..then paint. Good idea??

Are there any restoration shops you would recommend in the California area? And yes...I will not do anything until I read the book...Thank you for that advise...it's allready coming in the mail.

[pcford]

Mr. Morgan-

You have received some good advice. Certainly wise to stay away from epoxy in the seams. And yes polysulphide is preferable to 5200. (urethane)
I am not sure where in California you are located. Certainly in southern California or the central valley the conditions are more difficult for a wooden boat on a trailer. You might try putting a sprinkler inside the boat. After the boat swells a bit, maybe in a day or so, upt a 6" pipe nipple in the drainplug of the boat. This will all about 6" of water to stand inside the boat. NOTE: Be very sure that no leaves or trash plug up the pipe!! Boats can explode if you fill them with water.

If the seams get fairly tight you can seal them the rest of the way with Slick Seam. This is a waxy material with squeezes out when the boat tightens up with a day or two in the water. After that, if the boat is kept in cool shady spot, it will be ok if you use it a few times a month.

I have not read the Danenberg book but have read his comments here and there and his opinions sound very good to me.

I did runabout restoration for twenty years or so. Nothing seems to get an owner as excited as being able to seen daylight through the hull. But remember: what shrinks can swell. It's wood.

[pcford]

Slick Seam:

http://www.davisnet.com/marine/products/marine_product.asp?pnum=0730

This has no strength of course. It is just to hold the water out while the hull swells. People use it a lot here in the NW.

[Bill Morgan]

What worries me, after reading Danenbergs book is that after the previous owner used that method of filling the bilge with water until the leaking stopped is that the bottom planks have expanded and contracted so many times that I fear, as per Danenberg, that all solid connections between the bottom planks and the frame are now loose. I am in the process of removing some of the bungs (I think that's the name of the wood dowels that cover the screws) and test them to see if they are loose. I was definitely going to use the epoxy sealer CPES, then follow on from there.

The gaps/seams between the boards are very uniform at about 1/4" +/- and the bottom feels very solid. The problem is the fear that being this a 50 mph boat that the planks will break away and down she'll go.

It seems that I need a true professional to take a serious look at this boat before I do anything else. I have sanded the bottom and sides and the wood looks beautiful. There are a couple of cracked area that have been reinforced with screws...doesn't look too secure.

Thanks again for your advice.