Re: T&T: Fixed vs active fins
Once I took a group of twelve people out to see the fireworks in Vancouver.
Everyone wanted to be up top of course. I was amazed at how much easier the
boat was in a sea with a slow, comfortable and predictable roll. Everybody
was comfortable. For reasons I can not explain, the boat went noticibly
faster also.
Under normal cruising with just two aboard and inside, the boat is what I
call 'lively'.
Richard
She went faster because the weight lengthened her waterline. I believe the
anti-roll tanks are the solution. IMHO, they are not used on pleasure boats
because they require engineering for each and every boat. That means money.
In addition, if the end user adds a generator or removes one, that would
affect the calculation and the effectiveness of the tank. Some commercial
ships have these tanks.
Ron Rogers
-----Original Message-----
From: Richard Tomkinson
Sent: Sunday, September 11, 2011 10:38 PM
Once I took a group of twelve people out to see the fireworks in Vancouver.
Everyone wanted to be up top of course. I was amazed at how much easier the
boat was in a sea with a slow, comfortable and predictable roll. Everybody
was comfortable. For reasons I can not explain, the boat went noticibly
faster also.
Under normal cruising with just two aboard and inside, the boat is what I
call 'lively'.
Richard
Richard, another option may be to trade out the existing mast for one that is taller and heavier. As you noticed with all those people up top, adding weight up high can be helpful in slowing down the roll. Also, with a taller mast, you can add more sail area, which can also help to slow the roll.
When we built our boat, we just went out beside the shop and cut a tree down, hewed it into shape and installed it. You can also glue one up out of lumber. By considering the variety of lumber or tree (density=weight) and length, you just might come up with a combination that could replace those 12 folks. Add in easy-to-learn hand-spliced eyes and the standing rigging is inexpensive too, though you can go with mechanical fittings, but the cost will rise significantly.
All you have to do is to convert the weight of the 12 folks to a mast that weights about the same, well, not quite so much, as the mast will raise the height of the moment more, so the weight can be somewhat less. If not too sure of what size to make, just make the mast taller than you think you'll need. It'll be easier to cut down, than it will be to add length.
A taller and heavier mast may not do as good as an anti-roll tank, but it is cheaper, and, as you noticed with more folks up top, might just do the job well enough. Up there in Vancourer, with all those trees around, if you are up to the challenge you'll probably be able to find a tree for free, though you might have to spurge and buy an adz and steel tipped shoes!
Rudy
Briney Bug, Panama City, Fl
--- On Sun, 9/11/11, Richard Tomkinson capnrich@wavecable.com wrote:
From: Richard Tomkinson capnrich@wavecable.com
Subject: Re: T&T: Fixed vs active fins
To: "Trawlers-and-Trawlering" trawlers@lists.trawlering.com
Date: Sunday, September 11, 2011, 10:38 PM
Once I took a group of twelve people out to see the fireworks in Vancouver. Everyone wanted to be up top of course. I was amazed at how much easier the boat was in a sea with a slow, comfortable and predictable roll. Everybody was comfortable. For reasons I can not explain, the boat went noticibly faster also.
Under normal cruising with just two aboard and inside, the boat is what I call 'lively'.
Richard
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On 12/09/2011 04:10, Ron Rogers wrote:
if the end user adds a generator or removes one, that would
affect the calculation and the effectiveness of the tank.
I find the idea of an anti-roll tank quite enticing but this comment
from Ron gives me pause for thought. A long range displacement trawler
type cruiser would perhaps have 15 to twenty tons of fuel on board when
tanked up. A ocean crossing is going to burn a lot of that weight. How
would a anti-roll tank cope with that? Would you need to slowly
decrease the water, in line with fuel burn?
Paige
I was quoting another contributor. However, we are principally interested in
lateral rolling and not pitching. [Newer hydraulic stabilizers have brains
which can have an intelligent impact on pitching or at least not exacerbate
it. My 1985 units have had to be locked in larger waves taken head-on.]
Larger vessels can control fuel consumption balancing multiple tanks fore
and aft. Otherwise, tanks should be drained equally from port and starboard,
whether one has stabilizers or not. My 40 foot trawler displaces 20T and can
hold 600 gallons of diesel in two 300 gallon, side-by-side tanks in the
apparent meta-center of the boat. They drain equally. Just forward of these
tanks is a 300 gallon water tank. The tanks' levels directly affect fore and
aft trim, but there is little impact on the ride. I think that these
levels would have little or no impact on the performance of an anti-roll
tank. My vessel's heavy displacement does seem to make her more resistant to
wave action in general compared to other, lighter vessels.
David Cooper sure went from full tanks to near empty ones enroute from
Central America to Hawaii. I imagine that he would have mentioned it if
there was any negative impact upon his anti-roll tank's performance.
Ron Rogers
1985 Willard 40 FBS
-----Original Message-----
From: Paige
Sent: Monday, September 12, 2011 2:32 PM
On 12/09/2011 04:10, Ron Rogers wrote:
if the end user adds a generator or removes one, that would
affect the calculation and the effectiveness of the tank.
I find the idea of an anti-roll tank quite enticing but this comment
from Ron gives me pause for thought. A long range displacement trawler
type cruiser would perhaps have 15 to twenty tons of fuel on board when
tanked up. A ocean crossing is going to burn a lot of that weight. How
would a anti-roll tank cope with that? Would you need to slowly
decrease the water, in line with fuel burn?
Paige