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What is a 5200 bottom and why should I have one?

First a little history.....When Chris-Craft, Century, Gar Wood, Hacker, and nearly all the other boat manufacturers were producing these wood boats from the 1920s-1960s they constructed their bottoms to last approximately six to eight boating seasons. I suspect many of these manufacturers, if completely honest, would say they expected even less actual life out of the most important single part of any boat. Perhaps this was the first sign of ‘planned obsolescence’. That being said, it’s amazing so many of these classic powerboats are still running on their original bottoms…and many without any serious problems due to the viligent care and maintenance of their owners.

Even with the best maintenance, however, these original bottoms have long outlived their useful lives and many, if not most, have lurking problems underneath the surface where it’s not visible to the naked eye. I have seen many a bottom that on first examination all appears well…tight seams, good paint, no exposed fasteners, no cracks, soaks up in a couple of days, etc., etc. This really means very little unless you’re willing to get a little dirty by climbing into the bilge with an ice pick and flashlight and do some serious poking around in known problem areas. Remember, too, that during the ‘golden days’ of wood boating lakes were not as populated with other boats, or nearly as large of boats that use our waterways today. In other words, back in the ‘olden days’ they simply did not take the pounding of today’s lakes and were not designed to do so.

After replacing tens of bottoms one of the most prevalent problem areas are loosened, broke, or bent fasteners (they are after all, soft brass). Other common areas of trouble are bottom plank cracks following the fastener lines where screwed into the frames…again from the planks expanding and contracting over the years. Cracked and/or pushed out chines due to excess pounding and excess debris in the bilge, cracked bottom frames, and more often than not festering rot in the canvas between the inner and outer planking…where you can least likely see it. The two areas I find the most damage is about 1/3 amidships (close to the front seat) where the boat takes most of the pounding, and again near the transom where water likes to sit and spore rot over time. Centurys are especially bad near the transom, and I’ve never seen one that didn’t have some rot in the bottom transom frame.

Some old, and incorrect, remedies were to take caulking and/or linen of one form or another and fill the plank seams to get a ‘tight’ fit and stop that darn water from coming in. I’ve even seen bottoms where hard epoxy products were used to fill the seams. All these ‘fixes’ do are create and many times escalate the current problems by furthering the expansion of planks against already worn and very tired fasteners…resulting in an even worse bottom. These photos clearly illustrate how bad a bottom and its supporting structure can actually be...yet remain hidden until the bottom planking is removed.

OK, sorry for the long history lesson. A ‘5200 bottom’ as it’s known in the wood boating community is where you remove the current bottom, make repairs or replace damaged frames and chines, tighten and/or replace all frame bolts....then use new mahogany planking supported by marine grade plywood as the inner layer sealed in a proper and flexible wood sealer. The new lumber is attached with silicon bronze fasteners and 3M 5200 adhesive in lieu of the lead soaked canvas between the inner and outer layer. The 5200 product comes in a caulk tube which is applied to the inner layer (marine grade plywood) before attaching the outer mahogany planking.

It goes on like thick like paste, is spread to a consistent layer with a trowel and then remains flexible like rubber when cured. If done properly, 5200 will ooze between each adjoining plank seam to make a watertight, yet flexible fit. It’s also important to remove, clean (replace if necessary) the bottom transom plank along with the hullside chine planks, after all...those planks will be under the water along with the bottom. Again, it’s important to reattach those planks with 5200 to make both a watertight and flexible fit. To do the bottom and ignore those planks will still allow water in the bilge. It’s also important to remove and reseat both the rudder and shaft log assemblies in 5200. That’s it in a nutshell. It’s hard and messy work, and takes a lot of time to do it correctly. When finished, though, you will have a bottom that will not leak and, if not abused, out live you.

Why 5200 and not hard epoxies? Here’s the ‘Cliff Notes’ explanation…the wood in our classic wood powerboats is always moving—expanding and contracting with moisture levels and temperature…not to mention the natural movement as she pounds through the water. If the wood is always moving and hard epoxies do not, what happens? You end up with cracks in the epoxy and/or wood tearing from the epoxy as it comes under stress. This is obviously not good for the boat, resulting in even more damage that you started with. The 5200 is flexible and thus flexes and moves with the wood, eliminating stress cracks while it continues to maintain its water tightness. Need another example? Take two Dixie cups; fill one with hard epoxy and the other with 5200. After they cure drop them from head height. The hard epoxy will crack while the 5200 bounces.
Finally, the 5200 system bottom will increase the value of your boat by the amount invested in it. Ask any boat broker and they will tell you boats with properly done 5200 bottoms will bring anywhere from $8,000-$12,000 more depending on the size and model of boat.
Still not convinced? In my opinion one of the greatest advantages is the worry free aspect of these bottoms. Keep your boat on a lift or trailer and never, I repeat never have to worry about having to soak your bottom again. Put her in and you’re ready to boat. Your bilge will always be dry (except of course if you get rained on). Pull her out of the water and you’re done.



In the end, the 5200 system properly replaces the bottom of your boat, protects it from future rot due to sealing, flexes with your boat, provides the same ‘wooden ride’, looks original, allows more freedom in keeping your boat out of the water, and increases the value of your boat significantly. You decide.