A reply to an email enquiry.

Question:    Why a pontoon boat?

 Answer:    One of the things that amazes me is the number of (usually new) buyers who buy a boat with out a test drive.

They are spending a lot of money and as you know the performance of boats varies hugely, pontoon boats are at there best in harsh conditions….it is the confidence that is generated when you are in big seas knowing that the boat has positive buoyancy with a big percentage of that flotation being in the sides, where it should be, so if you do take a greenie on board, the boat remains stable, while the swamped water is draining while underway.

I have included a photo of a proto type that we regularly use to swamp to gunwale  level. Even with these large scuppers and "duck bills" it took 60 seconds to empty. That is a long time in heavy seas, worse when you are in a boat with basic flotation and you know in the back of your mind that it is prone to capsize when swamped.

The Typhoon boats web site has info on boat design and why the safety of RBBs are as good as it gets.

 

 

 

 

This is taken from a Boating forum abridged.

Safe boat size for offshore Nth QLD?

Question: from another nth Qld fisher has got me thinking....

Just what sized boats do people venture out to the reefs in and what size do you think is adequate for this.
Now I know some that have been out 40 odd k's in a 4m tiller steer tinny powered by a 30 horse and a couple of cartons but is there a rule of thumb or is it up to the sea conditions, experience of the skipper and seaworthiness of the boat rather than just the size???
If someone asked what the minimum sized alloy boat is and motor required to safely head 40-50 km's offshore ...what would you say???

 Reply:

It rather depends on the the design and build of the boat. Some 5 metre tinnies should not venture out of sheltered waters, by contrast a decent 5 metre RIB or its RBB cousin (Stabi /Typhoon) remain seaworthy in harsh conditions.
The feeling of safety comes from knowing that the boat has (full Flotation) compared to one of Basic flotation.
When it comes to safety, rBBs are as good as it gets.

A Forum members reply:

I would take a extra meter of boat over positive floatation any time outside in open sea, all positive flotation will do is make the hull roll like a marble after every wave. you would be far better spending your money on self draining decks and inflatable pc. just remember flotation has have to actually be in the water to be positive.

 Reply:

I would take a extra meter of boat over positive floatation any time when outside in open sea.
I think that most people would agree with you, however the difference in price between a 5.00 meter and a 6.00 meter conventional plate boat can be between $20,000 to $30,000, which is beyond many budgets, where as a 5 meter pontoon boat is only marginally more expensive than an ordinary boat, but in terms of safety a rBB is as good as it gets.

All positive floatation will do is make the hull roll like a marble after every wave.
A boat whether it has absolutely no flotation or has positive flotation will act exactly the same unless it is swamped, only then does the benefit of flotation kick in.

Just remember flotation has have to actually be in the water to be positive.
Any boat with under floor flotation has a big % of it’s flotation in the water, swamped or not. Flotation in the sides of the boat give it stability when swamped and allow it to float level, providing the motor is running and the boat is moving forward the water will drain through the scuppers.

A basic boat floats because of displacement not because of flotation.
Correct.

Flotation only works when it is submerged below water level.
Correct.

So these tinnies with flotation in the sides will float level drrrrrrr the only advantage is they float up right in a swimming pool
No disagreement there except for the bit following the drrrrr.

In a open sea a boat floating upright will tend to roll as each wave flows over the sides this can be more dangerous than basic floatation, with a Hull capsized but stable….this is why serious fisherman do not rely on this as there form of safety.
Now this is where you and I will have to agree to disagree. Boats with a large % of there flotation in the sides generally float level, and are relatively stable when swamped and are more difficult to capsize compared to boats without side flotation. Providing the motor is going and the boat is moving, the swamped boat will drain through the scuppers…..a lot slower than you might think. In a 4.7 meter prototype Rbb which we frequently swamped to overflowing, it took 60 seconds to empty from a standing start through large scuppers. As a result my designer came up with a "cat flap" transom door which emptied the boat in 6 seconds. I would rather be in a Boat with full flotation that stayed upright allowing the water to drain, than have a basic flotation boat capsize, with the wife and kids in the water, desperately trying to find something to hold on too…….I guess I just love my wife and Kids

 

 

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