increasing bouyancy with a given hull size

[H20Rat]

Re: increasing bouyancy with a given hull size

Btw, I run a 26x60 flat-bottom tunnel hull that will run in four inches of water on plane (for a few hundred feet anyway - but pretty much forever in six inches of water). This is with a 115 4str outboard and a 4-blade SS prop. Yeah, the skeg drags in the sand, but that just tells me to look for deeper water soon.

best case is that half of the prop or a little more has to be out of the water at that point.. Bet that is some impressive spray!

 

[ondarvr]

Re: increasing bouyancy with a given hull size

You are correct, it is far from a true drift boat design. However, the rocker on the hull lends itself to drift boat characteristics much more so than a typical hull. The rocker is designed for bouncing/sliding over shallow bottoms.

Btw, I run a 26x60 flat-bottom tunnel hull that will run in four inches of water on plane (for a few hundred feet anyway - but pretty much forever in six inches of water). This is with a 115 4str outboard and a 4-blade SS prop. Yeah, the skeg drags in the sand, but that just tells me to look for deeper water soon.

The difference here is that we don't have much sand, it's gravel, logs, and large rocks, if your skeg was to drag you wouldn't have it connected to you motor for more than about 2 feet. You don't get an oops I used the wrong line this time and drug the skeg, it's a big bang, the motor flips up, then RPMs go to the limiter, after that you just try to get back to the beach in some way without a prop and with a red face.

We would much rather use props here, they're much more efficient than jets, you just can't navigate the rivers with them.

 

[mrdancer]

Re: increasing bouyancy with a given hull size

Understood. You need to run a boat designed for the waters you run.

The river here is all sand/gravel bottom with a good mix of stumps, deadheads and widowmakers thrown in. Visibility in the water is limited to about six inches, but anything that close to the surface will make a ripple and you can avoid it by paying attention. With the tunnel prop, if I don't see it, I don't hit it. The tricky parts are the huge sandbars that slowly come up shallow and with the sun at a low angle late in the day (or this time of year), you can't see the sandbars until it's too late. That's how I know how shallow I can run.

Back on topic, the boat I am running has pods that are even with the bottom of the hull, so the boat is actually about 24.5 feet with about 16-inch long pods on it. The design of the tunnel throws water up to the jacked-up outboard prop and the pods help keep water around the prop - spray isn't too bad. Due to the hull dimensions and raised motor, the boat handles like a pig at slow speeds, but runs great on plane in the shallows. You learn to 'slide' the hull in sharper turns. Even though the boat is underpowered with the 115, it will get on plane in less than a boat length when lightly loaded, owing to the pods and double-cupped prop.

 

[Home Cookin']

Re: increasing bouyancy with a given hull size

sounds like a really cool set-up, and now i understand for the first time how the tunnel works to keep the prop off the bottom but in the water. Around here, about the only ones using them are net fishermen in the surf.

Every trip I am grateful for our mud/sand bottoms around here. Makes exploring much less nerve-wracking, and survival in the winter time marsh feasible.

 

[lncoop]

Re: increasing bouyancy with a given hull size

Mrdancer, a pic or two would be nice if and when it's convenient. Sounds like a rig many of us would enjoy ogling.

 

[giericd]

Re: increasing bouyancy with a given hull size

we have built pods for fiber glass boats and they do work great for displacement, but keep in mind that the water will not come off the bottom of the boat at the transome any more like it does now, you are sorta creating a partial tunnle hull by adding a pod on each side. we like to make the pods where they are not steped, we make them where it is like an extension of the bottom of the hull. this way it can hold more flotation and the tunnle hull effect can aid in running/getting on plane in real shallow water. the pod on the alum boats i saw are half above the water line when the boat is at rest and are stepped, that does not leave much flotation under water and it does not aid much in draft but more so in anti sinking, you want the flotation below the water line. just keep in mind any modification like this done to your bopat will make your boat handle totaly different, and you will notice when you are up on plane and trim the motor the nose of the boat does not rise much, wont be an issue for you with a 15hp tiller but your 14' will handle more like a 16' if the pods are done right

 

[mrdancer]

Re: increasing bouyancy with a given hull size

Mrdancer, a pic or two would be nice if and when it's convenient. Sounds like a rig many of us would enjoy ogling.

Here are a coupla pix from the boat builder. The boat has gone back to him for the winter for a few 'tweaks' and I should have it back in the spring.

The front rail, t-top and poling platform are all removable. The center console is raised above deck by 12" (really improves visibility). The helm seat is adjustable - there are no cushions on the seats or rod lockers yet in these photos.