LEVEL or LEVEL AND UPRIGHT Floatation?

[cormorant]

Surveyers know alot about conforming to the rules
They will get compliance
Bluntly your boat may float a little higher in the water in perfect conditions if swamped and if the calc has been done right and it will also float a little higher upside down so you have more to cling to but seriously no 300kg of positive bouyancy will stop the (active momentum) motion of 2 tonne of water rolling in your boat trying to get over your gunnels.

It'll help the rescue services find your hull quicker in a worse case and give you more to try and hold on to.

I myself would be very reticind to stay in a fully swamped boat in any serious swell due to possibility of getting tangled or injured by it's violent movement and risk of very fast capsize. Don't know what the experts say on that one but i know in the hobart they chose the liferaft over hanging around on board and risking injury

Seriously if what I have said doesn't click get a margarine container in the bath cut it down and add some foam floatation and a lead sinker and do an experiment.

Should say that floatation is a great idea and can lead to safer boating and better emergency outcomes but it should be placed well in perspective as a worse case scenario helper not saviour.

[snelly1971]

Well firstly ...The reason for fitting the added buoyance is so my boat will meet survey standards...as ...i will be in survey next month....and 2...where do you get the added 300 kg of buoyance from....

I am a very experienced boater..but i am not that cock sure of myself that i wouldnt fit more floatation either to my boat ..be it for survey standards or just plainly as a rec fisherman...even the best operators come unstuck sometimes...and gee wouldnt it be nice to have something to hang onto ...be it upside down or not...

I am not sure of the exact figures of floatation in my boat at present...but next month when the marine survey does his calcs then i will post them...

Cheers Mick

[snelly1971]

As for the Sydney to Hobart....If a boat has no propulsion or is breaking up ...then yes...i would also jump ship and get into a life raft....

Mick

[cormorant]

Well firstly ...The reason for fitting the added buoyance is so my boat will meet survey standards...as ...i will be in survey next month....and 2...where do you get the added 300 kg of buoyance from....

I am a very experienced boater..but i am not that cock sure of myself that i wouldnt fit more floatation either to my boat ..be it for survey standards or just plainly as a rec fisherman...even the best operators come unstuck sometimes...and gee wouldnt it be nice to have something to hang onto ...be it upside down or not...

I am not sure of the exact figures of floatation in my boat at present...but next month when the marine survey does his calcs then i will post them...

Cheers Mick

Dam Wrote a reply but can't get it to post

300kg positive buoyancy was a quick guestimate / number out of the air doing a quick calc of the space under the gunnel on a small boat.

I've been in a swamped boat after hitting a submerged object and it injured us when it violently turned turtle ,we were expecting it still the speed it rolled surprised us but once over it was a platform with a decent motion to hang onto until we swam to shore. No amount of floatation within reason would have stopped it going turtle due to cabin roof etc . In dead calm situation floatation may have slowed the violent turn turtle but it was inevitable as the slighest movement by any of us had the boat healing and then a small swell popped us over.

Until see actual fully rigged boats in a moderate swell not turn turtle I would worry about all the marketing hype on level floatation. Maybe for a runabout. Yes my boat is survey built and has floatation foam and airtight compartments so i know their value and wouldn't be without them. More floatation to a point is better but you don't want to end up with a boat that can turn over and then go over again. You need it stable platform in an emengency but as you say you want something to hang on to not a boat that goes to the bottom.

It concerns me that inexperienced people will take a unsuitable boat or a boat into unsuitable conditions because the believe the worst case is that it will get swamped , float level and they can either sit and wait it out or bail and get on their way. That is what I believe the pretty level floatation diagrams seem to promote. I don't believe many if any boats without a bloody big lead keel designed for self righting will ever do that. Most will turn turtle.

Absolute pain getting boats to survey standard if not originally built that way or upgrading to higher survey stsndard. Hope it goes well.

[builder]

If you need more info i have product information
I use it and navel archtects and surveyers love it.
1m3 will float a tonne
only abbsorbes 3% water and wont break down
fuel resistant
fibre glass international keep it in stock, Brisbane/goldcoast.
comes in 25mm.50mm,75mm and 100mm thickness 1200 x 2400mm sheets
4 sheets of 100mm make 1m3.
cheers

[snelly1971]

Thanks for the info Builder...I just installed 2 full 100mm sheets so that must give me an added 500kg of bouyancey.....They are currently doing the calcs on the sealed chambers and flotation that the boat came when built...

I can see your point cormorant....If a boat has extra flotation...it does not make it any more sea worthy ...just a little bit more safer ...well thats my opinion ...if disaster strikes....

The other difference between us....is water temp....it gets down to 5 deg here in winter in the bay and about 12 outside...so that is why i stressed the point about extra flotation....If disaster striked and the boat was upright/ or not ...it would hopefully give us something to cling/climb onto whilst waiting for rescue...

Cheers Mick

[snelly1971]

PS...I think by memory ...A person would not last very long in water that cold....I just cant remember the exact figures/hours...but i know it was not very long...

Mick

[cormorant]

Cold water kills and fatigues you quickly. Air is a poor conductor of heat and water is a good one. So if you can get as much of your body out of the cold water and protected on the leeward side of a boat you'll last ages longer especially if you can keep your head out of the water as major heat loss if via face neck and scalp.

Those cold water conditions a inflatable life jacket on at all times in my mind as your man overboard scenario is deadly fast.

Amazing the difference 1 degree in water temp makes. I scrub the bottom of a moored family boat and bow at about 18-19 deg water temp without any wetsuit I can go about 1 hour only in the water before the affects are getting serious and uncomfortable and I have a good coat of blubber!!! At lower temps like 17 it is like 20 minutes to get to the same point of near distress.

As long as the floatation doesn't end up being so much as to create a unstable rescue platform when turtle it is a good idea as I think we all agree now that boats don't stay upright very long when swamped offshore.

[fishing111]

Snelly or Builder have you got any photos of what this stuff looks like?

[snelly1971]

I will take some pics tonight and post them for you Paul..

Cheers Mick

[fishing111]

Thanks Snelly much appreciated.

[snelly1971]

Too bloody cold outside tonight Paul...I will post the pics tom...cheers Mick

[Lovey80]

Hi guys interesting reading. Builder what would 1m3 of that gear weigh? Must be some very very light gear to be able to float that much weight.


Cheers Chris

[builder]

not sure on weight but yes is light
i am guessing at 30kg