Bulbous bow.

Brian · 10-27-2006, 11:10 AM

Patrick Bray is a real expert in bulbs up here. He has retro fitted them to existing yachts to improve performance, done numerous tank tests and even incorporated them on hulls of 47' long, so not just for large boats.
Check his website, I think it's...www.brayyachtdesign.com

Innomare · 10-30-2006, 03:41 AM

Wow, all questions are answered already...

One that remains: empty or not?
Very often the bulb is part of the forepeak ballast tank. As it's so far forward, you need less ballast to correct the trim.
But I can tell you, it's a special experience crawling around in the bulbous bow with the usual 10 cm drab all over the place. Even the disposable head-to-toe boiler suits don't keep all the mud out.

On ice breakers: newer models have an ice-breaking stern. They go stern-first when breaking ice. This helps as their azi-pods suck the water out from under the ice. When the ships weight then slides on top, it's easier to break the ice. I guess for light ice, they just go bow first.

I've seen them in action. There is hardly a more impressive sight. In northern Finland you can take "ice-breaker cruises" for those interested in experiencing it. Included in the trip is a swim in a survival suit amidst the ice blocks.

Bruno

YachtNews · 10-30-2006, 08:51 AM

A survival suit just extends the life of the person in the chilly waters but you can still die if you stay in it for extended period of time...I wouldn't purposely jump into minus 0 water for the fun of it unless i had absolutely no other choice.

Francois · 10-30-2006, 10:02 AM

Bruno,it must have been something to crawl there and I am sure its a water tight bkh like welded to the structure with the bulb in fore position.Imagine hitting a container at see full speed on the bulb ,that could be a disaster.I guess the thickness must be at least one inch or more.

The ice breaking technic seems good but like yachtluver ,man I dont like cold water

.With tecnology their must be coming up with diferent ways for the bow to be more efficient when hitting ice.

Thanks and very informative.

Francois

Loren Schweizer · 10-30-2006, 01:53 PM

Quote:

Originally Posted by K1W1

Hi,

the heavy duty Ice Breakers rely on displacement tonnage and ****ty machinery balance and alignment to get where trhey are going.

Gosh, maybe he meant to say 'shifty'

Francois, in the realm of expedition/trawler vessels under 100 feet or so, the bulb has a greater job in reducing pitching in a head sea rather than any gains in hull efficiency.
Then, there are those troglodytes who insist that the absence of a bulb, especially on a larger boat, denotes a severe lack of manliness.

tantetruus · 10-30-2006, 02:46 PM

Quote:

Originally Posted by Loren Schweizer

Gosh, maybe he meant to say 'shifty'

Francois, in the realm of expedition/trawler vessels under 100 feet or so, the bulb has a greater job in reducing pitching in a head sea rather than any gains in hull efficiency.
Then, there are those troglodytes who insist that the absence of a bulb, especially on a larger boat, denotes a severe lack of manliness.

troglodytes

Kevin · 10-30-2006, 03:02 PM

LOL Caveman... someone uncivilised.

tantetruus · 10-31-2006, 12:45 AM

Quote:

Originally Posted by Kevin

LOL Caveman... someone uncivilised.

ah, one learns everyday

Innomare · 10-31-2006, 03:21 AM

Quote:

Originally Posted by yachtluver

A survival suit just extends the life of the person in the chilly waters but you can still die if you stay in it for extended period of time...I wouldn't purposely jump into minus 0 water for the fun of it unless i had absolutely no other choice.

Well, those Fins are a little different than you. They actually have clubs where they practice "winter swimming". That's swimming in a hole in the ice - without a survival suit!
And the best thing is... there are even waiting lists to join these clubs as they are so popular.

It's said to give some kind of adrenaline rush or so.
But not my cup of thea either, I must admit... A cold shower during sauna is as far as I want to follow their madness.

CanuckBoater · 10-31-2006, 09:42 PM

Interesting article about the bulbous bow in the Nordhavn publication, CIRCUMNAVIGATOR. If you download the PDF attached, it's page 26 of 212. For those of you with access to internet while on board, and any interest in Nordhavn or live-aboard lifestyle, consider reading both issues. URL for issue #2 is below.

I picked up both issues at FLIBS - good read on the flight home.

http://www.nordhavn.com/circumnaviga...avigatorII.pdf

(remember - bulbous bow article is on page 26 of the magazine above)