More Stuff Done Wrong

I might as well be on a grump roll here.
More Stuff Done Wrong.

pontoonibex
This pontoon catamaran, now a trimaran, was proudly on display out front at IBEX. Yes they are cheap compared to catamaran hulls. But, not only are they inefficient, they are not stable. And every time a pontoon boat rolls over, the USCG comes after the stable catamarans as well. Us.
First, look at that 175 hp motor. These are not all planing hulls so they will probably not exceed displacement speed of maybe 20 knots. Compare this to my 28’/32’ power cat that Matthew built. It’s about the same size. It has a pair of 15 hp and goes over 20 knots.
The stability is the real danger. When a pontoon boat is loaded past half draft, it gradually, then rapidly loses displacement. A typical cat hull gains displacement right up to the impossible total immersion. Several years ago a pontoon boat back East did just that with loss of life.
This unit has an even more dangerous feature; the middle hull. Clearly it was needed to amp up the displacement. The proper way would have been bigger hulls, but Skeeter uses what he has. The problem is if the center of gravity ever gets between the center of the space between the center hull and lower hull, the high side of the boat will begin to rise. This could happen if all the passengers went to one side to see something. If the center of gravity ever gets outboard of the center of the lower hull, the center hull is assisting overturning. It is much less stable than if it just had two hulls.
So, pontoon boats are already unsafe to carry many passengers due to decreasing displacement, but with the buoyancy kick up from the center hull, the overturning danger is much worse.
Some people might remember the article in this blog last spring ’13 about the narrow cat that rolled over in a beam on wave. A pontoon cat/tri like this unit is so narrow that it will be even more dangerous. Stuff done way wrong.

One thought on “More Stuff Done Wrong”

  1. Kurt,

    Thank you for your reply to my pontoon boat letter.
    1. You have shone that the 3rd pontoon is a poor option.

    2 .It looks like what your are recommending, is to build two new pontoons, that are large enough to raise the bridge deck, at least, an additional 12″. Increasing the distance from the water to the top of the deck from 12″ to at least 24″.

    3. Is there any way to use the existing pontoons and add the additional height to either the top or the bottom of the existing pontoons? Tough question without seeing the existing pontoons. I could send some photo’s. Thank you, Don

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