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bushbeachboy
10-03-2009, 01:24 PM
When you see a boat advertised with the term 'level floatation', what does that mean exactly? Will the boat float upright and level if filled with water? Or will it only float upside down and level? Or is it simply a generic term with little meaning, designed to help sell boats?

boatie_72
10-03-2009, 01:41 PM
Level means for a boat to float the right way up when swamped with all passengers still on board. But keep in mind that the test done is in swimming pool conditions (no waves, wind nothing). So it wont always stay up right in normal sea conditions. But there are so many standards the builder have to choose from and each one is different, for example CE does not include the weight of the motor when doing the calculations.

So keeping that all in mind is it worth it. Given that you will lose your side pocket storage for the builder to achieve level?

The whole standard is to try and make a set of standard for the marine industry but at this point in time it is to open and really doesn’t mean much.

Krashtackle
10-03-2009, 01:48 PM
Level floatation is when the hull is floating with its gunnels just above the water and in an upright position. Level floatation is not self righting.
Most of the boat manufactures that build aluminium boats to this standard do not have a fully welded self draining deck. The deck is usually wood or aluminium, but is not water tight. These boats generally have sufficient styrene floatation under the floor or under the gunnels so that the hull when flooded will sink all the way down to the gunnels - hence level floatation.

In laymans terms : meaning should the boat become fully

swamped the vessel will remain in a level and upright position in calm conditions

Hope this helps :)

Krashtackle
10-03-2009, 01:51 PM
Sorry Boatie!! Your post wasn't there when I posted...LOL

What

Krashtackle
10-03-2009, 01:52 PM
Sorry Boatie!! Your post wasn't there when I posted...LOL

What he said ;D

PinHead
10-03-2009, 04:44 PM
there are 2 types ..positive floatation which will keep the boat afloat when swamped with water and passengers on board...positive level flotation will do the same but will keep the swamped boat level also.

It should have been law here years ago..the yanks have had it law for a long time..all boat 20' and under must have positive level flotation and a lot of the builders also put it in their bigger boats.

gofishin
10-03-2009, 07:37 PM
...for example CE does not include the weight of the motor when doing the calculations...
Boatie, this statement is not correct. CE regulations stipulate conservative motor mass amounts across the entire HP range, in some cases a bit heavier than the 'heavy' for strokes. As of 2004, CE regs required more motor mass allowances for swamp tests in some HP categories than equivalent US regs, however there was not much difference.
cheers

White Pointer
10-03-2009, 09:07 PM
G'day,

The whole issue of flotation was studied in a magazine called "Plate alloy boats of Australia, Volume 4" which in still on sale. It is a complex issue (too complex for me to provide a synopsis) but worth reading.

Regards,

White Pointer

bushbeachboy
11-03-2009, 05:39 AM
Thanks for your replies. To take it a little further, look at your basic two-thwart tinny. Some are specified with level floatation, presumably from foam inside the seats. Will a boat like that float upright? If you look at some boats, they have very big thwarts and should float eg Stacer/Quintrex. Others have smaller thwarts and no specs about floating on their website eg Sea Jay. Does this mean that a Sea Jay will sink while another will float? What effect does the motor cut-out on a basic tinny have on how the boat floats?

boatie_72
11-03-2009, 08:27 AM
Thanks for your replies. To take it a little further, look at your basic two-thwart tinny. Some are specified with level floatation, presumably from foam inside the seats. Will a boat like that float upright? If you look at some boats, they have very big thwarts and should float eg Stacer/Quintrex. Others have smaller thwarts and no specs about floating on their website eg Sea Jay. Does this mean that a Sea Jay will sink while another will float? What effect does the motor cut-out on a basic tinny have on how the boat floats?

All boats sold within Australia must have basic floatation as standard. About 85% of all small boats sold here do have that. With most manufactures offering level as an option. Basic floatation means that the boat will still float just not up right. It was in most cases turn turtle with some part of the boat above water. The only thing quintrex do differently is (and you will see this if you take a closer look at their specs) for level floatation they reduce the number of people the boat can carry.

The effect of the motor cut out i.e. long shaft and short shaft will determine how much water the boat will carry when swamped. Having a long shaft boat will carry more water as the transom in higher. The water needs to find a level to equalize. This is why Quintrex/Stacer put scuppers on there larger boats, they are not for a wash deck but equalizes when swamped.

cormorant
11-03-2009, 08:53 AM
Regardless of what the manufacturers or reg say what will happen in a glassy pool assume that in real livfe with all the extra weight we carry that it will float. Which way up - well I am a bit more sceptical than most as I have seen a lot of photos with them upside down.

I'll be happy to have something floating I can hang on to as water acts very strange in a open hull in a swell. I frankly would rather have something 70 % sunk that is stable than a unstable level floatation all on the surface. It's not like you will get a chance yo bail it out in 99% of cases


I do like th Boston Whaler idea but again it is all about weight distribution.

Some dealers seem to like to overdo it and suggest it is nearly self righting and if I hear the word unsinkable I cringe but wifes like to hear that