Like the fixed keel, the lifting keel undergoes many mechanical and chemical stresses. Sooner or later, it ends up rusting, which requires a rigorous treatment to restore it. Here is a little tutorial on renovating a cast iron lifting keel.
Table of Contents
Removing the keel
The first step is to deposit the keel. So you have to put the aluminum Jon boat on the ground with a crane and prepare suitable support that will receive the keel. Preferably, use a roller rack to move the keel during renovation work.
The keel being a strong element (a few hundred kilos), the support must be strong enough to support its weight. Of course, before you start, make sure that the boat is correctly seated in the fairing area.
There must also be enough space to work comfortably under the keel. The removal procedure varies from one boat to another. So use your boat’s owner’s manual to locate the mounting bolts and the order of disassembly.
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Inspection of the lifting mechanism of the keel
There are generally two types of lifting keels: the pivoting keel that stays flush with the hull and the keel insert that fits entirely into the boat.
Ordinary swivel pins use a cable hoisting mechanism to lower or raise them. A mechanical or electric winch inside the cab guides the ascent and descent.
Most retractable keels use a hydraulic lifting system or a combination of hydraulic elements and electrical elements.
After removing the keel, the lifting mechanism should be inspected. On a pivoting keel, it is essential to check the condition of the shoe, the pivot pin, and the rings.
On a retractable keel, it is also necessary to check the condition of the cylinders and the viscosity of the hydraulic fluid.
Stripping is used to expose the keel and remove all dirt and oxidation. To begin, use a high-pressure cleaner (Karcher) to clean the keel.
Then use a sander and a coarse abrasive disc (40) to remove all traces of paint and rust. Be careful not to overemphasize the sander in one place, so as not to overdraw metal and have an even surface.
If necessary, fine-tune the sanding with a fine wire brush. In the end, use acetone or another degreaser to clean the etched surface.
Let the keel dry for 2 to 3 months, otherwise use oxalic acid to accelerate drying. Once the keel is completely dry, proceed to a new stripping to remove the fine layer of dust that has settled on the keel during the drying operation.
Since cast iron is a porous material, a coat of resin-based impregnating paint should be applied to seal any holes on the keel. This also eliminates surface defects resulting from stripping. Generally, use a single thin layer of impregnating paint.
Using a brush, apply the first coat of epoxy primer to block the porosity of the cast iron and promote the attachment of antifouling paint. Let dry for a few hours, then apply a coat of epoxy to smooth the surface to be painted.
Sand lightly using fine sandpaper. The more beautiful the paper, the better will be the attachment of the following layers. Then apply 4 to 5 successive coats of primer using a roller to form a kind of waterproof barrier between the keel and the water. Of course, the keel must be allowed to dry after each coat.
Finally, apply two coats of antifouling paint. Use a hard matrix antifouling for the first layer and an erodible antifouling for the second layer.
Rest of the keel
Generally, the keel rests in the opposite direction to the removal. However, it is essential to position the keel and using bolts and nuts fixing new.
Practical tips for the successful renovation of a lifting keel:
- Renovating a keel is an operation that requires a lot of time, so be patient!
- To avoid damage, it is necessary to use proper support to deposit the keel.
- Proper preparation is an essential condition for a successful renovation. So be sure to pick and clean the keel.
- It is essential to respect the drying time between layers.
- We must treat the entire keel. Otherwise, the water can rise by capillarity and infiltrate between the primary and the keel, which will reduce the protective power of the antifouling.