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Old 26-11-2007, 11:25   #91
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Sounds very strange. Two ideas:
1) Could it be that the frequency of the inverter is different?
2) Could it be that the washing machine checks the ground connection?

Both does not sound very likely.

In Germany there is a very helpful forum for electrical problems, if you do not find anybody who speaks german, you might even try in english:
Elektronik und Oldtimer Forum - Audio professional Crown Soundcraft Ersatzteile

Good luck and report your results!

Walter
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Old 26-11-2007, 21:15   #92
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Just for clarity,
The boat I refer to as beau boat is designed by me but I do not own the boat itself.
The boat now called "BeauJest" is owned by Christine Rich a friend of mine. She liked the concept enough to have me design and supervise the construction for her.
I am happy to supervise the construction of a similiar design and transport it via a 40 ft container, if anyone is interested.
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Beau Lyons
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Old 26-11-2007, 21:54   #93
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Quote:
Originally Posted by beau View Post
Just for clarity,
The boat now called "BeauJest" is owned by Christine Rich a friend of mine. She liked the concept enough to have me design and supervise the construction for her.
Same for me, I own nothing "on paper" either

Must be nice having a "Rich" friend

Dave
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Old 27-11-2007, 07:54   #94
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Beau,

I fully understand your disappointment over speed, and I can really sympathize with you. But ... I have to point out that you've designed and built an attractive, unique and very stable vessel. What an accomplishment!! Very few people can make that statement.

I suspect that your missing 2 knots must have something to do with the displacement formula, even without a bow wave. It's just too coincidental.

What's 2 knots anyway? Enjoy your beautiful boat.
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Old 27-11-2007, 22:35   #95
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Rick - I think Beau was looking for more like 20+ knots with 60hp burning.

I'm gonna guess it's interaction between the bow wake and the outriggers. Coupled with the excessive drag off the stern which is sitting low.

I reckon the water displaced by the bow is interacting somehow with the outriggers.
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Old 07-12-2007, 19:59   #96
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Beau
One thing I have not seen mentioned although it somewhat mirrors the concern about the main hull transom is the transom of the amas. Many modern trimarans have ama shapes more like a double ended canoe shape. The stern being more slender but rising clear of the water presenting no flat transom. A good example of this would be a John Marples Constant Camber 40CC or 44CC Take a look to see what I am talking about. My old Searunner has very narrow transoms on the amas and they are usually clear of the water until the wind pipes up or going hard to windward. I am also unsure of the reason for having the amas down by the bow. The speed problem may be a combination of many small elements that are adding up.
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Old 10-12-2007, 18:18   #97
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Thanks for your comments Steve.
I have placed 3 inch spacers under the rear outrigger arms, which has increased the buoyancy of the ama's this has raised the stern of the main hull 3 inches which is almost clear of the water.
A point you make is the waterflow at the stern of the ama's. they were at waterlevel and are now 3 inches below water (the width is 2 ft) I may have to lengthen the ama's to achieve a smoother rear exit flow.
Your point in interesting in that I need to look at which is the best way of achieving that effect vertical or horizontal or a combination of both.
I hope to start further testing later in the week.
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Old 10-12-2007, 18:54   #98
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Power to the people...

I know it's rather gross but have you considered bolting a much larger outboard to the back.

Something with an electric trim attachment.

Start with 80hp and move up to whatever the structural/weight limit is.

As you are only planning short trips it may be quite practical.

If you can borrow one the cost may not be large.
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Old 10-12-2007, 19:21   #99
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The original plan was to have two motors because I am NOT happy with one motor whether it be diesel or petrol for long range cruising.
One outboard was for long range (1000 miles plus) economical cruising at 9-10 knots. The other motor (much larger) was for 20 knots (get out of trouble)
The naval Architect who drew up the structural drawings convinced me I would be better to have two similiar motors hence two 30 hp Honda outboards.
Because of the extra weight I keep adding and In retrospect I would now go for two 40hp or even 50 hp.
However until I find the "sweet spot" with this hull design it is all very theoritical at this stage.
I do not get a bow wave which would "normally" slow this boat to about 8 knots, the hull is very sleek and I am still convinced that once I reduce the stern wave by lifting the stern clear of the water I will then get better performance.
Currently at idle with both motors I get 4 knots.
The outriggers are purely for stability (motor cruiser and down wind sailing) and I don't see why I can't lower the rear of the outriggers to add extra buoyancy to the stern where I need it.
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Old 10-12-2007, 19:43   #100
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"The outriggers are purely for stability (motor cruiser and down wind sailing) and I don't see why I can't lower the rear of the outriggers to add extra buoyancy to the stern where I need it."

Beau - This statement seems at odds with the theory of the boat. If the outriggers are for stability and you are adding blocks to their sterns to provide buoyancy they are now buoyancy devices and will definitely start adding their own drag to the system. In other words whatever drag reduction you are trying to get on the main hull will be transferred to the outriggers.

I love your concept but something has gone wrong from theory to practice and I am guessing it has a lot to do with weight and balance.

In my humble opinion this wedge shaped flat bottom boat wants to behave "like" a planing hull and if it is really light it will without the need of an engine to push it up on plane.

I am guessing that it's getting so heavy now that it won't. The inelegant solution seems to be adding hp until it planes. The efficiencies you predicted in my opinion have to come from somewhere unless we are bending the universe.

If you add big engines now you have to think about tankage for the thirstier engines. More tankage more weight - every designer since the begining of time has chased this demon. You will then reach the conclusion that you have a displacement boat, you will throw in a diesel mill for efficiency and live with 8-9 knots.

Get the weight out and get it balanced.

Just speaking out loud here.
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Old 10-12-2007, 20:26   #101
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Thanks Dan,
You are spot on. I am trying to hold on to all my extra goodies.
In Theory, with the bow depressed at a negative angle, there is NO hydrodynamic lift to make it plane.
Which might explain what is happening. Maybe by bow angle is too high.

Planeing is very expensive 50 hp per ton, I don't want the boat to plane. Displacement speed is only 5hp/ton (up to displacement speed) from then on I am in uncharted territory.

I have removed three of the large batteries , next is the washing machine?? but I then might get divorced that means even less weight on board. .

I will just keep testing so i get a better idea of what is really happening. I know I am on to something I am not quite sure what it is yet.
It is great to get opinions from others it helps me to question the base theory and keep my mind open to what is really going on.
It is not that hard to actually study the cause and effect (friction and turbulence) that cause the drag and then set about trying to minimize both.
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Old 11-12-2007, 00:00   #102
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Here's an interesting theory - what if with the nose down and the flat bottom up I actually create a low pressure under the bow and if I can keep the flow from separating it actually creates a reverse "mound" under the boat. The faster I go, the more "lift" I get under the stern and so in effect I am always boating downhill.

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Old 12-12-2007, 15:46   #103
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Dan,
I don't know whether, you are being serious with your statement, but yes i believe that is exactly what I have seen with the prototypes.
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Old 13-12-2007, 23:49   #104
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Beau,

It seems to me (without any necessary qualifications !!!) that you need to take some weight out and then get a very dense form of weight (eg lead) and be able to move it around easily while on a single voyage to see the effects.

YOu will then see instantly the result of moving weight.

Just an idea but not very well expressed perhpas.

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Old 14-12-2007, 14:41   #105
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yes, I agree.
Its called 200 amp/hr Agm Batteries.
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