Volvo D3 planing problem

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Polmary Peter

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volvo d3-160 with duoprop fitted to a 20ft O.Sullivan marine striker 20. When new managed to get 33kn and planed ok. 200hrs on clock volvo have checked everything changed many things. They have now suggested that when the starter motor failed they noticed rust on the flywheel and that the sensor that monitors the flywheel might be getting strange readings. Can this be bypassed/dis=connected? Currently engine revs at 2600 giving 13kn in ideal conditions! Very occasionally boat will plane but it is so intermittment that it cannot be replicated. Any ideas fuel bills going through roof
 
Went out with Volvo engineers in very heavy weather so unable to give thorough test. My opinion is that it is also a leg/trim problem. Volvo replaced the bellows/transducer on the leg and adjusted accordingly. I have noticed that the pistons in the hydraulic arms still protrudes about 3inches when the leg is fully down. Does anyone know if this is correct ? As always Volvo says they will check it on another boat but never do. You can see why I dont want to go down the route of the engine out to look at the flywheel sensor. My opinion is that it is functioning and yet another "sensor management problem" that Volvo think might be causing the problem. Vodia tests all done and no faults showing either. Clutching at straws springs to mind.

Cheers

Peter
 
Odd one.. in that you could originally get on the plane and achieve speed and now you cannot. To me this rules out a height problem on the leg such as is currently being encountered by a friend of mine who has a brand new Orkney 24. The leg needs spacers to drop it slight lower. Needless to say no-one who sold him the boat is falling over themselves to sort it.

My boat has a D4 and when fully timmed down there is very little of the ram showing, so if you have 3" showing then I'm guessing that that could be a problem (but of course there are so many leg variations this might be normal)

The other thing.. have you clouted the prop (does not need to have damaged it) - I believe that some of the legs have plastic thingummyjigs that are designed to break if you hit something (thus preventing worse damage) - If these have gone, perhaps the prop is just spinning beyond a certain speed. Maybe pull the props off and have a look?

Just a silly idea, but can you get any human ballast to move right aft and when fully down, see if that has any effect in helping you onto the plane? Also... and just stating the obvious, but are you dragging weed?

Re sensors.. Have they not hooked up their mini computer to your engine? This should tell you exactly what's wrong. I've been getting occassional orange warning lights - the computer said "check wires on fuel level sender" - My mate with the Orkney has also been getting spurious warnings and volvo told him that when the engine was fitted there might have been a bit of paint that's interferring with the sensors.
 
Sounds all too familiar with sensors giving intermittent faults. Any how when boat was out to have trim transducer replaced (thought to be original problem) it was anti fouled and Volvo had to remove props etc to replace bellows/transducers. So I'm assuming that the props are secure and spinning OK. Tried your human ballast trick but not much difference. The big giveaway that I think it is a leg problem is that a large volume of water is being pushed up even with the leg fully down. Talking to other people it seems to be a "catch 22" situation in that if not enough power no plane if leg angle wrong again no plane, which one it is Volvo dont know!!. Vodia box attached and nothing found. I cannot truthfully say when this started happening because I was blaming it on the transducer not giving me the correct amount of trim, but once this was replaced it still does not plane. If anyone has a D3 with the duoprop leg I would be interested to know how much of the piston is sticking out.

Cheers

Polmary Peter
 
What happens when you try and plane?
Is the back end getting shoved down into the water? If the leg isn't trimmed in far enough, more power just pushes the back end down, and you can't get any speed.
In my experience, you need the leg right 'in' to get on the plane, then progressively 'out' to stop pushing the bow into the water.
I think your leg trim could be the problem?
 
I too think its a leg problem but Volvo don't! Hence me trying to get as much info as I can regarding leg position etc. With leg fully down pushing large volume of water up (in my mind leg not down far enough) boat tries to plane but will not get above 2600revs if i change the leg (ie up) pushes rear down and revs drop (as expected). Cant seem to get it above this threshold. Very very occasionally it planes revs go to 3500 and the back end water displacement are fine, if I then drop revs and try to get back up on the plane back to normal with same problem. Has anyone got a D3 with duoprops that I can compare leg settings.

Cheers

Polmary Peter
 
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