LEVEL or LEVEL AND UPRIGHT Floatation?

[seabug]

Hi snelly,
There is a reference to Microlen on the page here

http://www.nmsc.gov.au/nrce_ap.asp?Product_Type=0

Check out number 23 on the list.

Regards
seabug

[seabug]

This Tasmanian site
http://www.mast.tas.gov.au/domino/ma...ml/fsGenSafety

Gives all the information one needs to work out the type and amount of floatation material required
It also gives instructions on cutting and installing the different products.

At $250-$300 for the average boat it is a very cost effective insurance.
Click on the URL above.
Then Click on Bouyancy in boats ,at bottom of right hand column,and then click on the PDF mark.

Regards
seabug

[FNQCairns]

Seabug, those links sent me on a journey that ended here:

http://www.tfifoam.com.au/index.html

Thanks for that

cheers fnq

[QuinnyDory]

I read a very interesting article in TBF early this year (I think...) from their resident naval architect that discussed what it means for a trailer boat to qualify for level floatation... and based soley on the logic presented it really opened my eyes. In summary, given a boat will float upright in reasonable conditions, it doesnt mean it will necessarily behave the same way when more than one person(S) is wandering around a swamped hull in less than favourable conditions and you have a huge inertial mass of water sloshing about (likely at a time when you have been swamped). Im no expert but it made me wonder about the whole situation and whether LEVEL floatation is a realistic prospect in weather that is bad anyway - maybe the best that anyone could expect is basic floatation anyway ?. My 2 cents.

[snelly1971]

So what do you think FNQ...???

[FNQCairns]

QD I think you are completely correct, the great amount of positive uplift caused by buoyancy underfloor when above floor is flooded and moving just flips boats quick smart. The only way around it is to have a gradient of buoyancy from less low to most high, don't think the manufacturers are interested in this as it would subtract from the visual and usable appeal of the interior, a boat built like this could I guess right it's self in theory given enough wave action.

The best a person who has basic floatation can do is add enough foam above floor that when the boat does try to turn turtle and a side dips entirely under water the added buoyancy (uplift) included by foam at that point is enough to halt the flip, then with luck enough water is then trapped inside that it all stabilizes albeit near totally flooded.

Those stabicraft and other boats of the same design have a huge advantage they don't need water to flood the interior to stop the flip, by the time the water is just trickling over the gunnel the outer tubes are exerting near full uplift to stop the flip.

Just gotta laugh at the adds for level buoyancy done on glassed out water next to a jetty, bungs out, with one guy on a stern corner and another bloke balancing him somewhere on the other side, both look to scared to scratch! might it all turn turtle! But a person can do that to any semi sealed floor boat I know because we completly flooded the under floor area on a 30 year old 18foot savage to get it under a bridge when the tide was rising to save 4 hours waiting, but we did have to put the bungs back in to stop from completly sinking.

cheers fnq

PS boats with ply floors and foam floatation underneath also have a great amount of air inbetween (that water will flood adding balast low)and have a better chance of staying upright than any comparably sized sealed floor boat.

[seabug]

I read a very interesting article in TBF early this year (I think...) from their resident naval architect that discussed what it means for a trailer boat to qualify for level floatation... and based soley on the logic presented it really opened my eyes. In summary, given a boat will float upright in reasonable conditions, it doesnt mean it will necessarily behave the same way when more than one person(S) is wandering around a swamped hull in less than favourable conditions and you have a huge inertial mass of water sloshing about (likely at a time when you have been swamped). Im no expert but it made me wonder about the whole situation and whether LEVEL floatation is a realistic prospect in weather that is bad anyway - maybe the best that anyone could expect is basic floatation anyway ?. My 2 cents.

Hi QuinnyDory,

LEVEL Floatation IS Basic Floatation. And is why a lot of abandoned boats are found floating upsidedown.

The LEVEL AND Upright Flotation is really the same result as that used in Stabicraft.
The Micolen in the gunnels equals the tubes on the Stabi type of craft.

By putting the right amount of Microlen under the gunnels the boat can stopped from turning upsidedown.

With those boats that allready have sealed space under the floor of the boat equal to the boats weight(Plate Alum boats with the self draining deck) it would mean that some of the underfloor volume needs to be reduced and that reduced volume made up by putting floatation under the gunnels.

Otherwise the boat would have too much floatation below water level and would still be top heavy if swamped.

One could reduce the underfloor volume by putting in wet storage lockers,catch bins etc.

Regards
seabug

[seatime]

Hi QuinnyDory,

LEVEL Floatation IS Basic Floatation. And is why a lot of abandoned boats are found floating upsidedown.

The LEVEL AND Upright Flotation is really the same result as that used in Stabicraft.
The Micolen in the gunnels equals the tubes on the Stabi type of craft.

By putting the right amount of Microlen under the gunnels the boat can stopped from turning upsidedown.

With those boats that allready have sealed space under the floor of the boat equal to the boats weight(Plate Alum boats with the self draining deck) it would mean that some of the underfloor volume needs to be reduced and that reduced volume made up by putting floatation under the gunnels.

Otherwise the boat would have too much floatation below water level and would still be top heavy if swamped.

One could reduce the underfloor volume by putting in wet storage lockers,catch bins etc.

Regards
seabug

There seems to be a big difference in the definitions of "level flotation" and "basic flotation"as are used when referring to the Australian Builders Plate markings.
Can't find references to "level and upright flotation", maybe level and upright have the same meaning?
have a look here ; http://www.safeboating.org.au/Builde...xplanation.asp

[seabug]

Hi Gelsec

Seems that there are different descriptions of boat floatation.

http://stinet.dtic.mil/oai/oai?&verb...fier=AD0767791

http://www.ultimate.com/omc-boats/lambrecht.html
Regards
seabug

[seatime]

Hi Gelsec

Seems that there are different descriptions of boat floatation.

http://stinet.dtic.mil/oai/oai?&verb...fier=AD0767791

Regards
seabug

that's an American report circa 1973, do you think it's relevant to Australia 2007, or terms used in this country present day. Even imported boats are required to comply with ISO standards which are similar to Australian Standards, "basic" isn't the same as "level" flotation as per current regs.

cheers
Steve

[seabug]

Hi Gelsec
Yes it is 1973
But did you read the second URL?

I am glad that lots of members have seen that they can make their boats a lot safer ,and have their families less worried if someone is caught in a storm ,for about the price of a good reel.

Regards
seabug

[seabug]

I read a very interesting article in TBF early this year (I think...) from their resident naval architect that discussed what it means for a trailer boat to qualify for level floatation... and based soley on the logic presented it really opened my eyes. In summary, given a boat will float upright in reasonable conditions, it doesnt mean it will necessarily behave the same way when more than one person(S) is wandering around a swamped hull in less than favourable conditions and you have a huge inertial mass of water sloshing about (likely at a time when you have been swamped). Im no expert but it made me wonder about the whole situation and whether LEVEL floatation is a realistic prospect in weather that is bad anyway - maybe the best that anyone could expect is basic floatation anyway ?. My 2 cents.

Hi QuinyDory,

Sorry ,my interpretation of some terms is in some places incorrect.
What I was trying to get across was that it would be much safer to be in the
boat in the top picture below.
Regards
seabug


Buoyancy for Vessels Less than Six Metres

Level Flotation – means that the boat will continue to float in a level position if swamped and will be prevented from capsizing in calm water. This will allow you to remain in the boat and bail the vessel to remove the water.



Basic Flotation – means that the boat will float in some form if swamped. If the boat has capsized, it will remain afloat for you to possibly cling to the upturned hull.

*These diagrams are illustrative only and apply in calm water.

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Information for Industry

The ABP is fast becoming law around Australia, so it is important for manufacturers to start developing plates to keep up with ABP legislation and regulation.
To ensure quality control of information on an ABP, only a builder, importer or competent person can supply and approve information on an ABP. A competent person is some-one who has acquired, through training, qualification or experience, the skills to approve information on a builders plate.
For further details, download:
FAQ - Builders
FAQ - Dealers

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[snelly1971]

Well the boat is finally back and finished....he is a few picks...

[deadbeatloser]

m8 that looks the go , bloody good idea , did the sheet metal work cost much? well done.

[deadbeatloser]

Well the boat is finally back and finished....he is a few picks...

ive got a 4.7 open tinny which i take 20mile offshore an hav found the transom to be to low,so next week end i am having a pod{2} stuk on each side of the motor{60 yam f/s}to give a bit of extra tail to stop water cumn over bak as it does. would luv 2 do wat u hav done.any suggestions?