Saltwater: Protecting a Small Aluminum from Corrosion

[mew]

Hi all! I have an aluminum Grumman Sport Boat with a 1954 Evinrude (see pic) that I want to take crabbing, but I'm leery of exposing the boat and motor to potential corrosion. I've heard of corrosion being caused by dissimilar metals in saltwater, which worries me because the previous owner replaced several rivets. I assume the rivets are aluminum, but I'm not sure. I've also heard of corrosion from stray electrical currents. I don't think that will be much of a problem since I'll be away from marinas.

I plan on crabbing for a max of 4 hours once a month or so. Do I need to do anything special to protect the boat and motor for corrosion? I'm assuming I can just run the motor in a nearby freshwater lake to flush it out. Thanks!

 

[kfa4303]

Re: Saltwater: Protecting a Small Aluminum from Corrosion

Hi mew. Neat old boat and motor. I used to run a 16' flat back canoe with a little 3 hp air cooled motor myself and I currently run a 14' semi-V tinny. Aluminum is perfectly safe to use in saltwater, however you will want to replace any hardware with stainless steel to avoid corrosion. Also, if the hull and/or motor are going to spend extended periods of time sitting in saltwater (i.e. days, weeks, months) then you'd want to add a sacrificial zinc anode to both the hull and motor, but if you're just making day trips rinsing the hull and flushing the motor thoroughly after each trip to the beach will be fine. Btw, I noticed you have a longshaft motor on that little transom. Building a small transom riser out of aluminum angle and raising the motor until the anti-vent plate is level with the keel will improve your handling greatly and reduce your draft. You may also want to consider making a tiller extender out of a small length of PVC. You simply cut a few slits in one end, slip it over the stock handle and secure it in place with a couple pipe clamps. I use one on my 20hp and it makes a huge difference. It will allow you to sit, stand or move around as needed to improve performance.

 

[JoLin]

Re: Saltwater: Protecting a Small Aluminum from Corrosion

I plan on crabbing for a max of 4 hours once a month or so. Do I need to do anything special to protect the boat and motor for corrosion? I'm assuming I can just run the motor in a nearby freshwater lake to flush it out. Thanks!

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Mew, a monthly outing isn't even worth thinking about. Outboard powered boats are slipped all summer around here without being flushed until they're winterized. It's never a bad thing to flush the motor after use, but don't drive yourself crazy over it. A pair of muffs on a garden hose might be easier than re-splashing the boat in a lake.

 

[kfa4303]

Re: Saltwater: Protecting a Small Aluminum from Corrosion

+1, with on exception, these old vintage OMC motors can't be run on muffs, so you'll need to submerge the LU in a test tank with the water level filled a few inches above the anti-vent plate. Btw, what year is the motor? It looks like a late 50s model 5.5-10hp. Love the boat too, very cool lines. Is it from the mid-west/west coast? I've never seen one quite like it.

 

[NSBCraig]

Re: Saltwater: Protecting a Small Aluminum from Corrosion

Just wash it off and enjoy it.

 

[mew]

Re: Saltwater: Protecting a Small Aluminum from Corrosion

Thanks for the advice! It sounds like I'm good to go as long as I remove any weird metals (I don't think I have any), wash the boat afterward, and run the motor in a test tank afterward.

kfa - I'm glad you like the boat! These boats were originally manufactured in the midwest and northeast coast, and I think you can still find them in significant numbers in the midwest (only a few have made it to the west coast). Mine works great for fishing and hopefully for crabbing as well. The motor is a 1954 Evinrude Fleetwin long shaft. I recently bought a new drive shaft and shift rod so I can remove the spacer and turn it into a short shaft. I've been wondering how much of a difference the shortening of the shaft will really make. Hopefully I can get to that project in the next month or so. Thanks for the tip on the tiller extension. I usually have another person in front to act as ballast, but when I'm alone it would be better to even out the load.

 

[kfa4303]

Re: Saltwater: Protecting a Small Aluminum from Corrosion

Cool little rig. The shortened leg will help quite a bit. Not only will it give you a shallower draft, but it will give you reduced drag as well which should increase the performance. Here's a pic of my tiller extender and grab bar. Lots of folks use this sort of set up down here in FL for running the flats (very shallow water).



NMZ in flight.AVI - YouTube (Here's how I run my boat using the grab bar and tiller extender. Btw, the boat he's using is called a Gheenoe and is a regional brand built here in FL. They're basically hot rodded, unsinkable, fiberglass canoes that folks use for everything from cruising on the lake, to saltwater fishing to alligaor hunting. They're like the mini cooper of boats.)