Plastic picnic spoons make perfect air scoops.
Once the holes are cut & there glued in place. I normally put a strip of light 2oz cloth & epoxy on the under/inside to secure them to the cowl
This is one of those things that tends to take me extra time during the building process. I use magnets and like them. The pulling force is simply amazing. Their weak point, if there is one, is side to side motion. I’ve had a cowl or two that I had to stop from being able to move side to side or front to back.
Great idea!
Interesting that you bring up their weak point, the side to side action. Zipp kits has solved this issue on the missile by putting a partial bulkhead on the underside of the cowling on both front and back. When you combine those two pieces with the front dowel pin, there is really no side to side or back to front movement of the cowling. The magnets should work for my boat if I can figure out a system to hold the rear tightly, but not so tight that I have to be Man Mountain to pull them off. I have a few airplanes that have canopies held on by magnets, and it sure is a great feeling to get a system put together where the canopy “snaps” on with magnets. The sound is cool to me…..(doesn’t take much to fascinate the simple mind…..)
Yeah I like the simplicity of them too. Sounds like your cowl will stay on just fine. Let me see if I can dig up a few pics of my past installs. Oh hey, on another subject, heat. The vents are a good way to allow heat to escape from your engine compartment. But make sure that all of your water passages are at least 1/8. If you take out the water nipples from the water jacket of a stock Zenoah for instance, you can’t slide an 1/8 drill bit through there. The same may go for your rudder , etc… I wound up going to Harbor Freight and buying an extended 1/8 drill bit and drilled out anything in the system that wasn’t 1/8”. On the water fittings for the motor, I held them in a pair of Vice Grips lengthwise and carefully ran the bit through. Use large diameter silicone water line too. I use some large black stuff I got from Gizmo Motors. I burnt up a brand new Zenoah because of this and it’ll never happen again.
They make hi torque servos that are standard size. The Savox 1210 SG waterproof servo gives you all you need and more. But they will run you 100.00. Good servos. I’ve never had one fail. The Pro Modeler DL270DLHV is one I’ve recently installed in my Backlash Sport Hydro. The features seem to exceed what others offer. I’ve only put it to the test once but performed flawlessly. The specs would indicate waterproof or highly water resistant , but I haven’t dropped it in a glass off water yet. Time will tell on durability, but I think it may be a good alternative to the higher. At half the cost I thought it was worth a try after researching a bit.
The pipe does get hot. Just make sure to make sure that the heat can escape. I think that boat has vents cut in the side which would help. You can maybe put some vents in the cowl as well. As far as the servo proximity, all you can do is try it. If it starts melting the plastic on the case, then you’ll know it might be a little close. If it doesn’t then you are probably fine. You could always move that servo back toward the rear. You would likely need to add a servo extension but the pushrod would be much shorter.
Overall weight and CG are important when building a boat but try not to overthink them. Have I in the past? Yes, guilty, but I don’t worry about them like I used to. Build your boat as light as you can without sacrificing strength and durability. As long as you are not puddling epoxy all over the boat and/or applying 30 coats of paint, you should come in around where it was designed to be. Don’t get me wrong, saving weight is good, a lighter boat goes faster normally.
