Heavy Boats Go Faster!

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Gludy

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As in the Soltron thread - my boats went much faster fully loaded with fuel and water than it did when only half full. I know that some of this nwas down to the soltron but in chatting to others, I have come across boat owners who claim their boat goes faster when fully loaded with fuel and water!

I think my performance gain was a combination of factors but it seems that the boat trims better when fully loaded and goes faster just because of the way it sits in the water - does anyone else have this characteristic?


<hr width=100% size=1>Paul
 
Hmm. You are breaking all sorts of scientific barriers with this new boat, Gludy.

The trim tabs on ours makes a massive difference. Did you do several runs with and against the wind? I sometimes try and do this but SWMBO tell me to stop being a nerk driving round in circles. ...


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Must admit our boat is not faster but is much more stable in trailing seas when loaded.

Chris

<hr width=100% size=1>Logged Sea Miles wanted for masters. Send PM if your on south coast and want skipper or crew.
 
My Princess tends to lean slightly over to port unless less slight trim is applied,I am suspicious of load distribution which I am looking into at the moment,boat next to me has just fitted a heavy full size cooker/oven and lost 3 knots in the process.

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Think you may have the same problem as me. For some reason one of my trim tabs works faster than the other. So with equal pressing time boat leans.

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Haydn
 
Is that 'faster' as in GPS speed or as in log speed? Have you done tests in both directions to negate wind and current factors? Has the log paddle wheel become freer as the boat is used more? Were the trim tabs in the same position both times? What were sea conditions like in both cases because waves will slow the boat down?
If you've considered all of the above, then you have indeed achieved a scientific breakthrough



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I have the same - mine's due to the stern rising to much in the water and losing 'drive' on the water. Dingy on the back and a full tank of fuel gives me a knot and a half on the top end

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"Is that 'faster' as in GPS speed or as in log speed?"
GPS SOG was what I was quoting. The log was sometimes just one or two knots different either way depending on the current.

Have you done tests in both directions to negate wind and current factors?
No. However, I do not think there was much difference on both days. In the solent the weather was about the same.

"Has the log paddle wheel become freer as the boat is used more?"
N0- boat was out the water before either trip and the paddle wheels checked. In any event I was quoting SOG.

"Were the trim tabs in the same position both times? " Yes - I need so little trin, just a touch on one and that was left from the first trip for the second trip.

"What were sea conditions like in both cases because waves will slow the boat down?"

Trial day was calmer than the trip when it went faster. In the Solent it was not much different but on the trip to Falmouth and then around lands end to Swansea the waves were big - mainly a f5, sometimes a f6 - we did slow down for just over 30 minutes in one section. So the waves were much bigger on the faster speed trip.

"If you've considered all of the above, then you have indeed achieved a scientific breakthrough"

Not really, I think the boats performance was supressed because the the buggy fuel - this was cleared by the Soltron. I also think that the boat must perform better with the extra 2 tons of fuel/water because it may sit better in the water.

The real test will come now when I compare cruise/top speed with low fuel/water with full fuel/water.

I am despite all the stuff on Soltron etc still amazed at what the boat is achieving with 2 600 hp engines. It has a lot of equipment on board such as a 20kv gene etc so to have such speeds available frankly surprises me.


<hr width=100% size=1>Paul
 
Mmmm. It really would be extremely unusual for a heavier boat to go faster. Normally, the heavier the boat, the lower it sits in the water, the more the wetted surface of the hull is and the slower the boat goes. On very small boats, it is possible to achieve a higher speed by putting weight forward to get the rear of the hull more out of the water but I dont think this is a factor with a boat of the size you have.
I think the jury's out until you've re tested the boat and the Soltron factor is nullified

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BPlease keep in mind that on sea trials top revs,which should have been 2250 could not be achieved. All we could get was 2100. This meant that we crusied at 1900 revs about 200 below top.

On the trip back after soltron - top revs could be achieved and we cruised at about 2050 rpm again about 200 rpm below top.

I am not going tpo anandon Soltron for a few loads of fuel to prove something to others - anyone can do the trail themselves if they wish to.



<hr width=100% size=1>Paul
 
Well, is'nt that the answer, then, or am I missing something? Soltron or something allowed your engines to rev higher on the second run with full tanks and the extra revs gave you a higher speed so nothing to do with extra weight

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No its not the whole answer.
The speed gain was large even without any extra weight. To make such a gain with extra weight as well cannot all be down to thje Soltron.

The extra speed, in my opinion, was down to the Soltron and the extra weight giving better trim. Others I know als claim to go faster when full of fuel.

I can test this by simply seeing what speed I do with low fuel and water tanks and if the persistant f8 outside Swansea marina calmed down for one weekend, I would !

<hr width=100% size=1>Paul
 
OK, OK, enough already! I believe your boat goes faster when it's heavier

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Re: Hurrah! it works.

I have replaced the aft cabin with a 30,000 litre extra diesel tank, with 10% filled with soltron, and have achieved a speed increase of almost 20 knots. Then, I invited 100 people to sit on the foredeck, and achieved an even higher top speed of 55knots. I am very excited about this reversal of Newtonian physics and I won't hear a word against it :-)

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Re: Hurrah! it works.

" have replaced the aft cabin with a 30,000 litre extra diesel tank, with 10% filled with soltron, and have achieved a speed increase of almost 20 knots. "
Excellent, if somehwta amazing performance but then so is the conversion behind it! :)

"Then, I invited 100 people to sit on the foredeck, and achieved an even higher top speed of 55knots.".
You did not state if they accepted your invitation. The invitation, in itself, adds no extra weight to the boat. Can we please be a little more scientific about this please? :)

" I am very excited about this reversal of Newtonian physics and I won't hear a word against it :-) "

Nope there is no reversal of newtonian physics:-

Soltron = Bug gone = higher engine revs = higher speeds

Fuller fuel/water tanks = better presentation of hull in direction of travel and/or better prop grip = higher speeds.

:)

Paul



<hr width=100% size=1>Paul
 
Re: Hurrah! it works.

Because their is less drag on the surface. Despite when under water they are in effect weightless - so when they come to the surface they add weight and go faster! :) :) :)

With a hull on the surface it must also be to do with the angle of presentation to the direction of travel. Its not as simple as just a direct reltionship between speed and weight.



<hr width=100% size=1>Paul
 
Re: Gut instinct

..and bullsh*t vs science again! ;)

"Why can a submarine go faster underwater than on the surface?

The submarine's "tear drop" hull design allows it to slice cleanly through the ocean when there is water on all sides. When a "tear drop" hull submarine is on the surface, a great deal of energy is used to generate the bow wave and wake. That energy is then unavailable for propulsion. The hulls of older submarines, like the World War II vessels and the first nuclear-powered submarine, USS Nautilus, were designed with narrow bows to move faster on the surface than they did underwater."
<A target="_blank" HREF=http://216.239.53.104/search?q=cache:8aA94oo6QJ4C:https://www.cnet.navy.mil/newlondn/subprimer.htm+submarine+faster+underwater&hl=en&ie=UTF-8>click here</A>




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