1960 Chris Craft sportsman restoration project

[rhtmarine]

Guys, I'm new to this forum... I'm currently working on a CC sportsman. I'm a 30 year cabinet maker with extensive experience in model race boat building and was looking for a large scale project. I bought this boat to bring it back from the dead.
After flipping the boat over, I have worked on removing the bottom planks. I plan on using the "Danenberg" method, using CPES and 3m 5200 sealant along with new silicon bronze screws to fasten the planks. When done correctly, It's been said the bottom can last 15 or more years. Pretty amazing since Chris Craft told customers to expect their boats to last 6 summers.

[gonzo]

You are destroying a classic. The Danenberg method is not my favorite, but may work if you design a boat for it. Otherwise, it is a very poor choice. Where did you get the information that Chris Craft told their customers to expect the bottoms to last six summers? Maybe you are refering to the caulk?

[PAR]

The Danenberg method is just as costly to preform as an epoxy bottom, doesn't last nearly as long and doesn't insure it'll be waterproof, which epoxy can. In the latest addition of Woodenboat Magizine, the three major reconstruction types are covered. Thought the author of the piece doesn't comment on the long term value of the 5200 bottom, it's clear he prefers either just as was done originally or the epoxy.

You'll find this is the case with most progressive restorers and repair personal. The 5200 bottom was once thought to be the cure all to some build types, much like those that thought CPES was the cure all to wood rot. The jury has been in on both for some time now and only the "throw backs" are clinging to old, disproven methodology.

3M 5200 doesn't "fasten" the planks, the screws do. 5200 acts as a bedding compound and if a trailer kept boat preforms this job fairly well, though future repairs will have someone cussing at the mentality of the previous repair person for using 3M 5200 rather then polysulfide.

I'm faced with simular discussion with clients and I strongly recommend they stop reading books by the likes of Pardey and Danenberg, who clearly haven't kept up with the advances of products, material/method testing and durability trials.

In short, you can get another 50 years from her,, using the exact methods previously employed by Chris Craft, possibly with some material substitutions. On the other hand, you can use an epoxied bottom technique that will produce a stronger, lighter and more water tight version, that will last at least as long, likely longer then the original or you can get a decade and a half out of a 5200 bottom. Your call . . .

[rhtmarine]

Well, somehow I knew that Gonzo would have something to say here...Par, you were right about the "fastening" term. Bedding is the correct term. I have another boat for family weekends at the river, this chris is a project boat that will see limited use. I have read about bottom work on these boats and feel this is a good method to carry out. Now, that being said, I'm open to constructive input. tell me more about the epoxy bottom. do you still plank it? or do you glass over ply?
I have talked to many restorers across the country, only sierra boat company suggests the "epoxy" method. all others spoke of the "Danenberg" method. At this point I respect the opinion of professionals. I don't plan on selling the boat for profit, I'm 50 and don't see doing this again.
thanks for your interest, Bob

[PAR]

If you're 50 and plan on living the expected life span of a 5200 bottom, you'll be doing this again before you're dead. Epoxy, your grand kids will be doing it.

With an epoxy bottom job, you can toss out the intermediates, which saves a fair bit of weight. An epoxy bottom stabilizes the hull shell, makes it stiffer and absolutely waterproof. The epoxy holds things together and the fasteners are a secondary consideration. The bottom can also be a whole bunch "fairer" too. With this type of bottom, you can usually save even really ugly bottom planks, but not so with a 5200 bottom, where the planks must be sound. A 5200 bottom 5200 is just a modern bedding, other wise is essentially the same as an epoxy bottom. It also takes a lot longer to do a 5200 bottom, because of the cure time on 5200.

Pick up a current WoodenBoat and read up on it. The primary difference between the 5200 and epoxy bottom job is, the 5200 bottom uses CPES to partly waterproof the wood and 5200 to take up the moisture content changes, while epoxy makes it completely waterproof so there's no dimensional changes in the bottom, wet or dry. Lastly is the cost issue, which we all worry about. It costs more to do a 5200 bottom, because the planks have to be sound and the 5200 costs more then epoxy.

[rhtmarine]

Par, I appreciate your input, I do. So, I have all new lumber, bronze screws, CPES, and 5200. I've used epoxy and it's very expensive in large quantities. At this point I'm sticking with my plan. However, I'm not opposed to listening and reading further. I'm still working on removing the old bottom.
Thanks, Bob

[Surfszup]

Your thread might have hit a dead end.

Asking for further advice while continuing a build in your own way is like asking some one to waste their breath.

Good part is, if someone offers REALLY REALLY good convincing advice, you can still return the 5200 supplies.

Otherwise, I've worked epoxy, never used the 5200 stuff.....I like the epoxy.

I'll let you know how long it takes for my kid to destroy the epoxy boat tub I built last year.

[rhtmarine]

surfsup, I think you are missing the point here... I do appreciate all the input and comments. I didn't ask for opinions though, I only posted my project from an interest standpoint. As far as time to build with epoxy verses 5200... pretty much the same. cost wise, epoxy may cost more. The thing I like about the 5200 method is that the bottom is soaked as the 5200 cures, thus eliminating the swell factor. I'm not putting anyone down for their in site, quite the contrary. I am happy you guys jumped in. At this point, I'm still leaning toward the 5200. I have talked to many professional restorers and NONE except Sierra has recommended epoxy. To me, it seems that a glass boat is a glass boat, and a wood boat is a wood boat. only MY opinion and 2 cents
Bob

[rhtmarine]

Guys, one more note, 3m 5200 is not a new product. In fact, it has been around for years. I'm very confident of my research, and will continue on with my Classic restoration.
thanks everyone for your input, IT IS appreciated!
Bob

[Surfszup]

My apologies I will pay attention next time I read. I was thinking you were looking at two different methods and chose one. Quite the contrary, it was you stating what method you were using and others stating their opinions.

Thank you for posting your restoration project. I think you have a nice boat in your future. I personally see a 1934 woody wagon when I see your boat......classic

[gonzo]

Adding a rigid bottom to that hull will damage the sides, transom, bow stem and deck. If you want to have a monocoque construction, go all the way and redo the whole boat.

[rhtmarine]

Originally Posted by gonzo

Adding a rigid bottom to that hull will damage the sides, transom, bow stem and deck. If you want to have a monocoque construction, go all the way and redo the whole boat.

Gonzo, I'll pretend that every professional classic wood boat restorer that I have spoken to knows nothing, and you know everything. NOW, back off this thread. You offer no usable data...
Bob

[rhtmarine]

Originally Posted by gonzo

You are destroying a classic. The Danenberg method is not my favorite, but may work if you design a boat for it. Otherwise, it is a very poor choice. Where did you get the information that Chris Craft told their customers to expect the bottoms to last six summers? Maybe you are refering to the caulk?

Chris Craft did not use caulk...

[gonzo]

I may not give you good news, but wishfull thinking does not get the job done. Information on methods that don't work is useable if you want to face reality.

[PAR]

Actually the hull becomes quite rigid Gonzo, without difficulty. Because the frames are bonded to the bottom just makes the structure stiffer, but doesn't prevent the other elements from moving if they so desire. The new bottom doesn't move, nor do the lower futtocks, but everything else is still mechanically fastened. Load transmission is still permitted and over a larger portion of bottom, then a straight mechanically fastened bottom. The resulting structure is better in a lot of ways. The first thing noticed is hole shots are much crisper, again because the bottom is receiving and dispersing loads much more uniformly then the original or 5200 bottom can deliver. There's much less creaking and moaning, there's no bottom flex in rough water, the chines stay put, so the topside planks live longer, etc., etc., etc.