Re: Here we go PODS project with pics
Well, the basic idea is quite sound... RIB boats use an extra length of their tubes back behind the transom for the same reason.
But, I don't think intuitive engineering is going to serve you too well here with regards to attachment of the pods to your hull.
First, make sure you fair the pods with respect to your hull, and the transition between them and the main hull is as smooth as possible. Any ridges will create turbulence that will create drag and slow you down.
Second, the connection to your hull with those four bolts (are they actual bolts, or carriage bolts?) looks weak.
When the pod is in the water, there's a fair amount of upward force on it... you're looking to use its buoyancy to lift the rear of your hull up, after all. That thrust will be very hard on those bolts, especially when a big wave hits. Think of the case where a big wave catches you from the aft from a wake or similar.. there will be a moment when only your lower leg and the pods are in that wave, which may be big enough to lift the pods the height of the hull.. for that moment, your two pods are going to be trying to dead lift your hull, fuel, you, and everything in the boat up.
Put another way, would you consider putting a strap on the pods, lifting the rear of your hull up, then getting in the boat and jumping up and down? If it won't handle that without cracking fiberglass you likely need a stronger joint.
Another thing is that the main force on those bolts isn't straight up and down. When the pods lift up, they want to swing up on the transom like a barn door. They'll put force on the face of the transom and pull up and out on the bolts in addition to shearing upward on them.
If you're going to use bolts, I'd do the following:
1) Spread them out more so they are near the corners of the pods.. that will limit the leverage from torque the pods get on them
2) Use backing plates instead of just washers... either glass on some 1/2" plywood backing plates or better yet use aluminum plate about 1/4" thick on both the inside of the transom and the pods. The force on those bolts will at least equal that on cleats, and you wouldn't install those without backing plates, right?
3) Test extensively before going on the water. Try lifting the boat using the pods, try jerking on it while it's in the air. It's not just going to be static weight pulling on the joint.
As said, I like the idea though, and I've been considering buying/building a boat like that, with tubes or pods on the back.
Erik
no i didnt use anything to figure them out i just thought i want them big enough to go past the motor and as wide i could.
