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Old Jan 04, 2010, 01:02 PM
FROM THE MIND OF A MADMAN
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Any way to cure this little problem ?
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Old Jan 04, 2010, 02:07 PM
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Any way to cure this little problem ?
Which problem?
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Old Jan 04, 2010, 02:55 PM
FROM THE MIND OF A MADMAN
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Whatever problems you may see
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Old Jan 04, 2010, 03:07 PM
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Have you got the rest of the photo showing the stern as well as the bow? go
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Old Jan 04, 2010, 03:55 PM
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Sydney, Australia
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Gpzy,



My 2 cents. The boat sits to low in the water. How heavy is it? From other pics thought it was just too much weight at bow. The above photo looks like more than just a 'nose-diving' problem going downwind. Looks like she wants to be a submarine.
I'd try to lighten the boat. Waiting for someone with more experience as I think we all have IOMs that 'nose-dive'.

Larry.
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Old Jan 04, 2010, 04:07 PM
FROM THE MIND OF A MADMAN
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Larry that boat was over built. Heavy . Can't lose any more weight.
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Old Jan 04, 2010, 04:50 PM
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USA, LA, Mandeville
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Can you adjust the bulb back a little on the keel? And do you have the nose of the bulb canted up a few degrees?

How overweight is she? How much does your sail winch weigh? You can get a digital arm winch with 402 oz/in of torque (29 kg/cm) that only weighs 2.4 oz (68gms). It just takes money HS-7950TH


Look for photos of Craig Mackey's Patriot, or Steve Landeau's boat to see how they ride in the water.
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Old Jan 04, 2010, 05:05 PM
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Sydney, Australia
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Quote:
Originally Posted by gpzy View Post
Larry that boat was over built. Heavy . Can't lose any more weight.
You could always lighten the bulb (lead ballast). Move batteries as far back as possible. Might even suggest you have to move the keel back. Anything to lighten boat and get nose up.

How much does the boat weigh. How far off 4000g? Mike (from WA) has a heavy boat but I assume his still sails OK since he races her. Your boat looks very low. Hence must weigh a ton. Are you sure the hull displacement is correct? ie who built the hull and does it have adequate buoyancy.

My Noux2 IOM weighs about 4.5kg. But it looks nothing like your boat when sailing. The bow / hull sits on the water line when sailing. Downwind, like most boats, the bow has a tendency to go down. But not under water, on a reach, like your boat.

What is the depth of your hull at the mast. Deck level (gunwales) to bottom of hull. On my new IOM build its 130mm. If your boat is lower this could be the problem. Not weight but hull is too shallow. We had this discussion about low hulls on the Emo build thread and compared some hull profiles. The Emo bow was about 25mm lower than average. Some owners posted that this made no difference to sailing.

Below is a pic of the last USOM I built. I lowered the gunnels on this boat for looks. Still, depth of hull (deck to bottom), at mast, is 120mm. It has never 'nose-dived'.

Larry

*
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Old Jan 04, 2010, 05:49 PM
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Gpzy posted photo DSC-6125 which appears to be a crop of Larry's patriot-05
The bit I was interested in is at the back.


Somehow this thread is back to the beginning. To stop a broach without the ability to sheet in the jib, the rudder is pulled on good and hard, that slows the boat down making the problem worse, the nose will displace as much water as she needs to to get a balance between the sails and the nice powerful rudder.
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Old Jan 04, 2010, 06:12 PM
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gpzy,

Have you had the boat floated in a tank? How did it float? Bow down etc?
What is the rigged total weight of the boat in question?
How much cant on the bulb?
Is the mast and fin position as per Craig Mackay's boat?


The hull design is not a bad one and should certainly behave better than what is shown.
Without us knowing the above the best you can hope for is an educated guess.
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Old Jan 04, 2010, 06:20 PM
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Not my boat. I was just the photgrapher. I was just amazed at the booms dragging in the water.
This boat actually sails well in light to medium wind. Only when it gets to almost b rig wind does it turn into a submarine.
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Old Jan 04, 2010, 06:21 PM
FROM THE MIND OF A MADMAN
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Not my boat. I was just the photgrapher. I was just amazed at the booms dragging in the water.
This boat actually sails well in light to medium wind. Only when it gets to almost b rig wind does it turn into a submarine.
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Old Jan 04, 2010, 07:10 PM
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Perth Western Australia
Joined Jul 2009
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From the sounds of it the boat has to larger rig when a gust hits it it nose dives, so it may holding the larger rig to long when the wind picks up.
I have the same Problem with my Ts-2 Clone, if i hold a larger rig to long it will nose dive down wind too, Hew has the best idea move the bulb and angle it up a couple of degrees. In regards to losing weight i had to change rudder servo to a mini servo only 12g, changed the rigging to 11mm sailsetc mast and super light weight booms, changed the batteries from NiMh to LiFePo4's, changed the servo mounting from Aluminium and ply to Carbon fibre, changed the rudder from fibreglass to Carbon Fibre and then stripped the paint back to fibreglass (7 coats) and put 2 light coats on. All up 500grams was saved, but the boat still weighs 4300grams.
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Old Jan 04, 2010, 07:13 PM
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Remember that ANY model sailboat, heck any sailboat, will bury the bow if the wind is more than the rig can handle! That is the best way to see if you need to move to the next smaller rig.

This is not necessarily a broach either. My boat will nosedive in a big puff downwind, without me touching the rudder. If the boat can not accelerate fast enough to keep the sails from loading up too much, the bow will go under.

Sometimes you can bear off a little slower, at the top mark, and let the boat accelerate as you turn, and the bow will stay up. Once on the run, if puff hits, you can sometimes depower by a)Trimming the sails in a little, or b)Bearing off till you are by-the-lee and the jib is blanketed by the main.
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Old Jan 04, 2010, 09:57 PM
k4s
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A few more pics of a TEMPEST 2.
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