2nd opinions on prop selection

[rudderless]

If I were to design a 3 tube style I would make the center tube flat on the bottom the full width of the tube. I don’t think it would take away from the displacement efficiency all that much and might lift the outer tubes out of the water some..but I’m just a ghetto boat designer…

[jerry-ahrens]

Most of the big tritoons [25 to 28 ft.] I service, are running 150-300 hp outboards. Some have V8 Mercruiser power. They vary from Honda, Suzuki, Yamaha and Mercury 4 stroke’s and Verado’s. The center tune being oval, or ”egg shaped” makes it like a new boat so to speak. The boat takes turns much the same way as a v bottom hull, and leans into the turn, instead of away from it. Traditional pontoons make the occupants feel like they need to hold onto something in the turns, to stay in their seats. This new construction virtually eliminates this. I also had to buy a new heavy duty trailer, just to be able to haul these boats out for service. The old flat trailers won’t work anymore because of the big center toon. Manitau boats have a gigantic center toon, one of the most oversize I’ve seen.

[fisherman6]

Thanks Jerry. That is what I figured and that makes sense. I can understand that. It just seems to me that a pontoon with a 25-70hp motor would not see the benefit of this design. With 150+ hp, yes.
-Ben

OldJohnnyRude on YouTube

[johnyrude200]

So I used the boat again yesterday for several hours and paid closer attention to some of the points brought up here. I found that at near WOT, the boat is acting like a traditional V-hull but the 50hp just doesn’t have quite enough power to get the center tube much out of the water. The bow lifts, the outer tubes get about 1/3rd of the way out of the water, and the center tube might be 1/4 out. So yes, drag is an issue as the boat is basically plowing like a typical V-hull that can’t climb out of the water.

I also did some WOT corning and noticed the things you guys mentioned about stability. The boat does lean into corners like a V-hull (not away), and is very stable on turns. You almost notice no difference on a sharp corner at 16-18MPH. Of course, when not fully on plane, there wouldn’t be much leaning anyway.

I’ll probably bump up to a 70hp motor for next season just to experiment with things to see how it does. The center tube came off a 20′ grumman (trimmed down to 17′ now) that was rated for 70hp, so structurally I think the boat will be OK so long as I don’t beat the hell out of it in a bad chop (say 2-3′ waves).

The weight difference between the 70 and 50 with power trim is only 50lbs so we should be good.

[Author]

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