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Old 06-07-2008, 17:51   #166
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Speed and Safety

Thanks for that response Dave.

I totally agree with all you have said and would not dream of going cruising before I have practiced with drogues and parachutes to get to know the boat and become familiar with the routine.

I am only looking for speed, if possible, as an added weapon and this is basically what you also say.

My cruising grounds are around the UK Channel Islands etc. I am based in a port that has a tidal range of almost 40 feet. I am an experienced boater on cruising power boats.m Often we need a bit of speed to make a lock and it can laos be handy for reaching a harbour ahead of a gale.

The cat is intended for both Uk and blue water work.

My direct question to you is do you think that a lighter cat is less safe in a storm? Can you simple reef down earlier or put the drogue out earlier?

So I am assuming that all the good seamanship actions are taken - just looking at the one variable - the displacement of the boat. I am talking about comparing say a 7 ton boat to a 12 ton boat both about 46 feet.

I have been reading your web site tonight and found it fascinating.
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Old 06-07-2008, 18:16   #167
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Quote:
Originally Posted by Gludy View Post
Thanks for that response Dave.

My direct question to you is do you think that a lighter cat is less safe in a storm? Can you simple reef down earlier or put the drogue out earlier?

So I am assuming that all the good seamanship actions are taken - just looking at the one variable - the displacement of the boat. I am talking about comparing say a 7 ton boat to a 12 ton boat both about 46 feet.

I have been reading your web site tonight and found it fascinating.
My fully loaded Privilege 39 weighed ten tons when lifted out of the water in New Zealand. So my comments are based on my experience with ten tons of catamaran that are 39 feet long and twenty-one feet wide.

From my personal experience, I would not be so much concerned about the displacement of the catamaran as I would be about the strength/quality of its construction. If the lighter and heavier displacement cats are all strong and well-constructed, I would be happy to cross oceans on either of them.

The principles of storm managment are the same. It's just that some designs are capable of higher terminal velocities and faster acceleration. At the low end of the spectrum, you can't go slower than zero knots. So drogues and parachutes work their magic in the same way at the low end.

Fast cats are more dangerous in the sense that they have more kinetic energy that you must control at all times. If all that energy gets out of control, bad things can happen. Capsize, pitchpole, and structural damage are extremely poor ways of dissipating uncontrolled kenetic enery.

If I was on a fast cat sailing at high speeds in marginal conditions, and I wasn't going to slow down, I would have someone standing in the cockpit with a sharp knife next to the mainsheet and someone standing next to the genoa sheet ready to cut the sheets if they should jam in an emergency. Again, it's not rocket science. It's common sense.

If I was on a fast cat, I wouldn't ever let things get to the point where I needed to carry around a knife as part of my sailing gear.

For me, displacement would not be an issue. No matter what the displacement, I would sail it in a manner in which safety was not a problem.

Even if I had a Gunboat catamaran that sailed at twenty-five knots, it would still probably take me ten years to do another circumnavigation.
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Old 07-07-2008, 02:13   #168
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It may be just me but it seems there is an air of associating strong with heavy and weak with light. It is easy to build heavy and weak, especially when building to a price range for the masses. Light and strong gets expensive and also benefits from lower stess if both are in the same situation, not withstanding Daves comments about speed which I agree with completly.

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Old 07-07-2008, 02:19   #169
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Heavy needs to be stronger to start with since the stresses on a heavy boat are much more than on a light weight boat.

Greetings

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Old 07-07-2008, 02:50   #170
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Heavy/Strong

I agree that light should not be equated with weak.

In Dave's own lecture he points out that in bad weather you need to reduce the energy in the boat. The energy is very dependent on speed but it is also dependent on mass. So a 7 ton boat traveling at any speed will have half the energy of a 14 ton boat traveling at any speed. (Mass times velocity squared).

Therefore a light boat on a parachute traveling at 1 knot will have less energy to bang against the sea than a heavy boat traveling at 1 knot on a parachute - therefore the light boat, providing it is strong, must be safer than a heavy boat according to Dave's own logic .......... agreed?
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Old 07-07-2008, 02:54   #171
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Hallo Paul

The nice thing is with a fast boat you can always slow her down by using less sail area
but how can you go fast with a slow boat ?

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Old 07-07-2008, 04:01   #172
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Hallo Paul

The nice thing is with a fast boat you can always slow her down by using less sail area
but how can you go fast with a slow boat ?

Greetings

Gideon
Gideon
How perfectly put and how true, this has answered a lot of my questions.
excellent.
Thanks
Ian
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Old 07-07-2008, 05:06   #173
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Hello Gideon
I think you are right, although if the speed under bare poles is too fast you may have to deploy a drogue or parachute earlier - agreed?
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Old 07-07-2008, 14:33   #174
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What speed did you make for the Arc in the 435?
Gludy... We averaged 7.5 over 2900 nm using main and genoa only. Broke the gennaker after 2 hours use (incompetence) The course is 2700 but we didn't follow the rhumb line.
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Old 07-07-2008, 14:52   #175
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Quote:
Originally Posted by Gludy View Post
Hello Gideon
I think you are right, although if the speed under bare poles is too fast you may have to deploy a drogue or parachute earlier - agreed?

Yes I agree when the speed is to high deploy a drogue or Parachute or even better a Jordan series drogue, these work much better in storms and slow the boat fantastic ad with the shocks from a parachute.
Before we do that we first lower our retractable motors and the large 17 to 18 inch props will slow you down considerable while charging your battery system.
At hight speeds I expect to be able to slow with 2 to 3 knots with both motogens down.
We will know in 2 or 3 months when the first Fastcat 455 is launched with the Green Motion system.

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Old 07-07-2008, 14:57   #176
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Quote:
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Gludy... We averaged 7.5 over 2900 nm using main and genoa only. Broke the gennaker after 2 hours use (incompetence) The course is 2700 but we didn't follow the rhumb line.
I find that a very good speed condsidering that a gennaker is really a must over that course with winds swinging between 100 and 180 degrees normally.
Chapeau Bas

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Old 08-07-2008, 16:24   #177
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I find that a very good speed condsidering that a gennaker is really a must over that course with winds swinging between 100 and 180 degrees normally.
Chapeau Bas

Gideon
I cannot claim the credit Gideon. It was a good wind year!
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Old 21-07-2008, 13:31   #178
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Talbot;

The 37 came in a couple of configuration. My 37 has two heads. One on the starboard fore hull. It includes a seperate shower. The other is in the master cabin. It has a combination shower/toilet in this hull, the sink is outside the shower/head area.
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Old 21-07-2008, 13:40   #179
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My 37 had plastic thru hulls until I replaced them all. I replaced them with some very cool titanium thru hulls. Now the only problem with these were that I could not find titanium seacocks. Therefore, I had to replace them with forespar/plastic (okay fiberglass reinforced plastic) Seacocks. One of these days, someone may a titanium seacock, I'll be ready!

In any case, I did not have a failure, just a concern. Someone told me I was supposed to be able to stand on the seacock/thru hull. The plastic just wasn't doing it fo me.
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Old 21-07-2008, 14:35   #180
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A couple of years ago, Titan Marine Products told me they were about to bring out a line of Titanium Seacocks &/or Valves.
Apparently, they havenít, yet.
Marine Hardware - Titanium, Great Advantages Over Other Hardware
Notwithstanding, titanium (thru-hulls) will mate with standard Bronze Valves, without significant (dissimilar metals) problems.
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