Tube height

[Arctic RIB]

Doesn't it seem like the tubes are too high to really have any affect except on very sharp turns? Wouldn't that defeat the purpose of a r "I" b? Maybe it's just lightly loaded.

[seawolfribs]

Originally Posted by Arctic RIB

Doesn't it seem like the tubes are too high to really have any affect except on very sharp turns? Wouldn't that defeat the purpose of a r "I" b? Maybe it's just lightly loaded.

The RIB in the picture is loaded with 1.3 tons of fuel, and has been designed to carry a very heavy pay load, as they are workboats.

[Arctic RIB]

Wow that's a lot of fuel, it is a very nice looking RIB, on other work RIB's it seems the tubes are closer to the water near the transom effectively increasing the beam giving different turning characteristics in shallow turns and also much less roll in rolling seas? I guess what I'm wondering is wouldn't it handle more like a conventional boat in force 4+ seas? I suppose you would save on fuel and have a higher top speed. I'm no expert boat builder just making observations. Maybe it's just because the RIB is travelling at a high rate of speed causing the hull to plane very high out of the water.

[codprawn]

You do have a good point - many boats these days are just normal designs with tubes attached - not a true RIB as you say.

The 9m above is on the borderline I would say - with a good load and at lower speeds or in big waves the tubes are still doing something - unlike some designs where they are just there for fendering!!!

[Hightower]

Welcome seawolfribs.

My tubes are in the water even when I'm on the plane, but when is a RIB not a RIB. I mean, there are designs out there where the tubes are miles out of the water and you could even execute a high speed turn without them getting wet, take em out into a F7 and they still aren't realy doing any work.

On my RIB the tubes are a part of it's design and without them wouldn't work. Is it that with outher designs they're just an added safety device and little else?

Andy

[seawolfribs]

Originally Posted by Arctic RIB

Wow that's a lot of fuel, it is a very nice looking RIB, on other work RIB's it seems the tubes are closer to the water near the transom effectively increasing the beam giving different turning characteristics in shallow turns and also much less roll in rolling seas? I guess what I'm wondering is wouldn't it handle more like a conventional boat in force 4+ seas? I suppose you would save on fuel and have a higher top speed. I'm no expert boat builder just making observations. Maybe it's just because the RIB is travelling at a high rate of speed causing the hull to plane very high out of the water.

The tubes are slightly higher to allow for a heavy pay load, she has been tested in heavy seas, force 8+ and is very stable, she has been tested by military forces both home and abroad.

[Richard B]

This debate about tubes in or out of the water comes around from time to time, and there a few interesting points which have been made. One of the most interesting I think was Mark Wildeys account of the difference in handling he encountered when he once had a puncture in the rear section of the tube on one side. No difference at all.

[codprawn]

Originally Posted by Richard B

This debate about tubes in or out of the water comes around from time to time, and there a few interesting points which have been made. One of the most interesting I think was Mark Wildeys account of the difference in handling he encountered when he once had a puncture in the rear section of the tube on one side. No difference at all.

Well if that's the case we may as well all get rid of our RIBS and join boatmad instead!!!

[Richard B]

Originally Posted by codprawn

Well if that's the case we may as well all get rid of our RIBS...

You haven't got yours yet!

and join boatmad instead!!!

You did! http://www.boatmadforum.co.uk/member...nfo&userid=457

Truth is that different designs of RIB use the tube in different ways, and you need to know why you want/need the tube. For high speed, keep the tube clear of the water when planing. For stability at rest (diving/fishing etc), you need at tube that's touching or in the water at rest. But if your RIB depends on the tube inflation to keep afloat, that's bad design. And if your tube is in the water at speed, you will have very poor high speed handling. I suspect that many RIB owners who think that their craft suffer from chine walking at speed actually suffer from tube-bounce. Good hull design will give you all the high speed and rough weather capabilities that either a RIB or non-tubed hard boat needs, but the tubes will give you one thing that it's difficult to get without, and that's buoyancy when swamped, making RIBs safe in conditions where this a possibility.

[Jonny Fuller]

Now there's something you don't see very often!

A ribber wot finks..

good explanation Rickardo!