3 Outboards Questions? 2 Props 1 Jet Unit?

I was just wondering if this setup would work okay. I need the jet drive for shallow water situations, otherwise I won't use it much. This is going to be for a 52 foot by 16 foot landing craft that I am going to build myself. Also, how far apart do you think I should put the engines? Should I use a counter rotating pair of props since the jet unit OB will be in the center, or should I just use regular engines? Also, has anyone seen how the steering setup is on something like this? I want to be able to steer them all from one wheel, but the jet unit will be out of the water most of the time. Any help would be greatly appreciated. Thanks

 

Just saw this thread - and am curious about your project. It's hard to envision what you have in mind, and how a dedicated jet drive makes more sense than tunnels, or jack plates, barge and tug, or other approaches. For a landing craft this size, have you looked at Winninghoff's (?) Sea Sleds?

Sal's Dad

 

I plan on having a transom jack, a Porta Jack or similar, IF I decide for sure on going with outboards. At the very least I will probably go with outboards for the two outside prop units, and maybe have an inboard jet. I am going to take a look at the Winninghoffs, I have only been looking at Munson and Sea Ark so far and I am going to build something similar unless I run across something better. What I am looking to do is build something really light and able to plane when empty, but strong enough to haul a 50,000 pound water well drilling rig, its a twin rear axle Reichdrill T-650. BTW, thanks for the reply, this thread has been up for awhile with no reply. Ben

 

How about a "catamaran" approach, so it floats high on two long narrow flat keels (maybe 4' x 50') when light, and settles down onto the big bridge deck barge portion (8'x40'?) when the rig is aboard.

A couple outboards could be mounted on the bridge deck transom, so the props are barely in the water when light, and project no lower than the pontoons.

What are your draft limitations?

 

I thought about pontoons if I had to really limit myself financially, but they would eliminate or limit my use of a jet unit, which I need because this boat will be used on a river that can be really shallow in places during low water years and especially in September/October of any year. The river (Yukon) runs pretty fast, about 7mph, so that rules out any type of barge-like craft, which I wouldn't want anyway. My ideal boat would be something that would do 40 or better against the current unloaded and consume around 30 gallons per hour or less. I can't predict speed and gas consumption loaded, but I have a good idea of what I can do unloaded. Going downriver, obviously, I don't even have to use the engines for long stretches at a time. Munson has a pontoon type craft, the PackCat, which is really an air entrapment type CAT hull, but that will complicate the building process for me. I am looking at a design that I and one helper can build in 2 months or less with a minimum of equipment, i.e. a 10 foot brake, a Miller 3 in 1 welder, and a plasma cutter.

 

Also, if I were to use a pontoon boat, it would have to have a 48 inch wide center pontoon in addition to the 30 inch wide outer pontoons, just to support that much weight, and it would not get near the gas mileage of a regular hull. The ability to plane unloaded makes a huge difference on rivers when gas consumption is a concern, which it definitely is to me because this is a very remote area. Gas in my town is 3.85 per gal, diesel is 3.50/gal, so anything I consume I have to bring in from Fairbanks myself or have a wholesaler bring in, which requires a minimum of 1000 gallons I believe. I have a 40 foot gooseneck trailer, so bringing it in by the drum is what I plan on doing because it will have to be in drums on the boat anyway.