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Bill H

Pump Boat Rudders How I made one

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Bill H

My original pump boat (not built by me) was a dog to steer. Very hard to turn, very hard to control at slow speeds; just not what I like to see in any boat. The problem was the rudder. It was too small and poorly designed. I use the term design loosely. In fact, it was simply a flat piece of stainless steel sheet welded onto a stainless steel shaft. Here is what it looked like:

 

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Note the shaft is undersized and had a distinct bend in it, further evidence the shaft was not up to the job.

 

Here's another view of the rudder, in it you can see the rudder is clearly just a flat steel plate welded onto a 1/2" stainless steel shaft.

 

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Both the Rudelie I (original boat being rebuilt) and Rudelie II (new build of my own design) needed a better rudder. Here is what I came up with compared to the old rudder off the Rudelie I.

 

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As you can see, the new rudder is a bit larger. This will give us better control at slow speeds. It also has a hydrofoil shape, which will make it more efficient and it is balanced. That means the rudder shaft is positioned well behind the leading edge. This makes turning the rudder much easier, particularly when the boat is moving faster. For those of you who are more technically inclined, here is how we built it:

 

We started with three blocks of 2 x 6 Karot wood, the same wood we used to frame the hulls on both boats. Using a drill, router and chisels, we hollowed out the center of the blocks to accommodate the steel core of the rudder as seen in the following pictures.

 

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We wanted the three blocks to fit pretty close together and accept the stainless steel rudder core without binding. You can see how we accomplished this in the above pictures. Once we had the correct shape and fit, we inserted the stainless steel core.

 

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Next we clamped the three bocks together with the stainless steel core in place, using wax paper to prevent the epoxy glue from gluing the clamps to the wood. Then we poured the liquid low viscosity epoxy glue into the gap between the wood and stainless steel core. I expected there to be some leakage, and there was, but we just brushed the wet epoxy on the outside of the rudder to protect the wood and let the whole assemble cure. A few hours later, we mixed a second batch and did another pour, which leaked very little and we let that harden over night. The next morning, we did the final pour, filling the gap right up to the top of the wood. Here is what it looked like then. The epoxy did several things besides bonding the three pieces of wood together. It filled all the voids around the steel core, which eliminates any possibility of water entering and causing dry rot. It sealed the wood, and made it stronger and less susceptible to marine borers and it protected the wood from minor damage and abrasion.

 

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My original plan was to use 1" stainless steel shafting, but it was not available when we went to purchase it, so I had to settle on 3/4" stock. We used 3/16" diamond plate for the extensions because we got it surplus at a good price. The plate serves to strengthen the wood and prevents the wood from rotating around the shaft. I'm cautiously optimistic the shaft will be robust enough. Time will certainly tell if it is. One of the challenges of building boats here is the lack of materials and parts. We constantly find ourselves jury rigging things because what we want to get just isn't available, or is prohibitively expensive. In a few days, I will post some pictures of the steering system we built which is an excellent example of what I'm talking about.

Edited by Bill H
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Cannonball

Hello Bill,

 

Thank you for the enlightenment about fabricating a rudder, thats a bridge I still have to cross. I need to build it big enough to turn 98 feet plus bamboo amas 4 to 5 5 inch pieces on each side each approx 30 to 40 feet long. I will be pushing the boat with a 34 inch prop I haven't settled on the pitch yet, but it's going to require a substantial rudder. Any advice you might have would appreciated that feel like sharing. Thank you for listening, Braun.

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Bill H

Hello Bill,

 

Thank you for the enlightenment about fabricating a rudder, thats a bridge I still have to cross. I need to build it big enough to turn 98 feet plus bamboo amas 4 to 5 5 inch pieces on each side each approx 30 to 40 feet long. I will be pushing the boat with a 34 inch prop I haven't settled on the pitch yet, but it's going to require a substantial rudder. Any advice you might have would appreciated that feel like sharing. Thank you for listening, Braun.

 

Sure be happy to help. Send me an email with more details or PM me.

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Cannonball

Hello Bill, I believe I have about 23 more posts to go before I can PM you or get your e-mail. I'm busy working (7 / 12's) a week over here, we have seven fun filled Mondays a week, so I don't have allot of free time to deveote to reading the forum and posting comments. I should be home mid Dec +or- maybe I will have enough posts by then. Thank you for your patience and help.

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Headshot

Hello Bill, I believe I have about 23 more posts to go before I can PM you or get your e-mail. I'm busy working (7 / 12's) a week over here, we have seven fun filled Mondays a week, so I don't have allot of free time to deveote to reading the forum and posting comments. I should be home mid Dec +or- maybe I will have enough posts by then. Thank you for your patience and help.

 

Just go to "Contact" at the top of the page, and ask Paul to send your email address to Bill. Then Bill can email you.

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Bill H

Got the message, sent an email, problem on the way to being solved.....I hope.

 

Bill

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Bill H

The guys launched the boat in my absence and just completed sea trials. We're going to have to twick the prop a little bit as it seems a tad undersized. The rudder works beautifully! No modifications needed, so we'll do another for the Rudelie I and hopefully be launching her shortly after I come home.

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