This article is about electrolysis on wooden boats. More often than not, wooden boat owners are unaware, that wooden boats are at risk as well as metal boats for deterioration from electrolysis. Please keep reading!

Recently, I spoke to several groups of people from a wide variety of professions; they seemed to be surprised electrolysis can have such a profound impact on everyday life. I thought this might be a very good time to include some information on electrolysis as it pertains to wooden boat bottom construction or replacement as well as tips to do and not to do. I am not an engineer, nor is this a lesson in metallurgy, but it is worth reading and becoming aware of how metals, water and electricity interact with each other – on wooden boats.

You might know if you’ve been following my articles, we are replacing the bottom of a 1960 cris craft, 24’. This information is particularly interesting and appropriate because the boat was just finished at another boat shop, and when the owner placed the boat in the water it began to take on water and started to sink in the boat slip. The boat was saved and delivered to the shop for investigation. Starting to remove multiple bottom planks there were multiple problems, poor re-fitting of the transom, large open gaps, bondo filler and stainless screws holding the planks onto the hull. The boat bottom was reassembled with stainless steel screws on a boat that had all brass fittings; this combination of mixing metals is a perfect scenario for accelerated deterioration of a boat bottom. Hull wood had deteriorated into mush. Upon removal the brass screws and bolts, crumbled or broke off as spongy pieces

CrisCraft originally built the boats with brass screws, not intending the boats for salt water use. Credit goes to the boat builders of yesteryear, after years of service the boats have held up pretty darn well. But today’s boat owners are in a unique situation: trailering the boats is easier than ever, which means you might use the boat in both salt and fresh waters. Perhaps you own multiple boats, new ones, older models on the cusp of needing a bottom repaired or replaced; or maybe you had a boat bottom redone and do not know which type of metal fittings the Boatwright used below the water line. As a boat owner you need to be aware of how dissimilar metals can be affected in fresh and salt waters, you need to be aware that other boats in the marina can affect your boat even when you’re just tied in a slip; but more importantly than those two critical things you need to be aware that shore power is the most destructive source of electrolysis.

Click HERE for complete story.

Thanks for your question; it’s a very good one, every owner of an old boat wonders about the same thing. Here’s how I handle old boat bottoms.

First the history~

Years ago when the CrisCrafts and other similar boats were being built, they did not have the products that we have today. In years past, bedding compounds were made of lead and linseed oils and used to keep water out of the hulls. The Criscraft bottoms were double planked with canvas and bedding compound between two layers of wood. The canvas kept the water out until the outer layer of planking swelled tight. Years later the bedding compounds would dry out and loose their sealing ability.

Often boat owners in an effort to stop the water from coming into the hull when the bedding compound was deteriorating would stuff caulking of some type into the outer layer of planking seams. This temporary fix seemed to be okay UNTIL the swelling planks had no where to move so they pushed up and outward from the keel pulling the frame ends apart at the chine. This resulted in a huge problem, the boat was falling apart. If you re-build a bottom using the old system, the same thing will happen.

Propelling forward into today’s technology ~ the 5200 modern bottom. If you use this system, the boat is double planked and 3M’s 5200 is used as a sealer and adhesive between the two layers and planks. This system seals the planks where they are glued together.

In addition, an epoxy sealer is used to seal the visible parts inside the boat and the outside of the hull thus totally encapsulating the wood. Just before the outside is sealed, spray the planks with water to bring the planks up to the proper moister content. This moister actually swells the planks to their optimum size, seal the planks at this time and the planks will keep that size.

In the photo you will see I cover the bottom with sheet plastic to keep the moisture from drying too quickly. The wood does stay stabilized, it won’t (or shouldn’t leak), this eliminates the wait time for the planks to swell, like yester-year, and best of all the boat will not fall apart.

I don’t know your level of boat carpentry skill, but the bottom is the most important part of the boat – for if it doesn’t float, game over. There is a lot to doing a bottom, plank spacing, when to do what, how dry is too dry? Is the wood too moist? On and on it goes. The best thing you can do is be totally honest with yourself, can you really do the job right? It is so cool to work on your own boat – but, maybe you can do a different task on the boat for bragging rights, just NOT the most important job. But, whether you do the bottom yourself or use a boat shop, you should learn more about the about the moisture content of wood, encapsulating, and the epoxy systems, so you can talk shop with your Boatwright and have an understanding of what he is telling you.

There are multiple books available to read – all offer something valuable, even if it is to know don’t do it that way or YES, this is the way. One book you should add to your library is Don Danenberg’s book;

How to Restore Your Wooden Runabout, from MotorBooks ISBN 0-7603-1100-5

We are very lucky these days with all the modern sealants available.

So, the modern bottom is pretty neat, it is much stronger, doesn’t leak and lasts many many years. I use the 5200 3M System on all my boats. This is all my opinion and others may differ, but I have years of proof and grand results.

I completed a total restoration of a 1955 Criscraft 22’, recently and have included some photos of the bottom re-do for you to view. To view more photos go to my Sandra Lynn Boat Works website, click on CrisCraft and view the many photos posted. If you go through the photos you’ll see a pictorial of what will go into re-doing your hull bottom. You might find the whole restoration interesting viewing.

Readers, let me hear from you and the questions you have – I’ll pick one that would apply to the most readers and do my best to answer them, from my experience.

Karl Weinert, Master Boatwright

Sandra Lynn Boat Works, LLC
Big Sandy, TN

http://SandraLynnBoatWorks.com

http://TennesseeBoatSchool.com