56' MY can it plane>

[Scarlett]

I just surveyed a 61 cockpit motor yacht yesterday, which is a 56 with a 5 foot cockpit. It had 12 71 TI and was very light, no dingy, 1/2 fuel very little furniture and not personnel items at all. Engines were in great shape but that boat did not get up on plane either 2350 Rpm about 14 knots only. I thought that was a bit slow. Had 32x31 props polished and in perfect condition. John

[kjcampos]

I just surveyed a 61 cockpit motor yacht yesterday, which is a 56 with a 5 foot cockpit. It had 12 71 TI and was very light, no dingy, 1/2 fuel very little furniture and not personnel items at all. Engines were in great shape but that boat did not get up on plane either 2350 Rpm about 14 knots only. I thought that was a bit slow. Had 32x31 props polished and in perfect condition. John

Scarlett 15 knts was our best in Tampa Bay in calm water and right out of the boat yard with new bottom paint about 3/4 fuel 150 gal. water about 50 gal. holding tank same furniture i bought the boat with and also no dingy...Trim Tabs fully down at 2250 RPMs

[rsmith]

How much fuel and water do you have aboard? Where the tanks are is critical also. My water tank is the most forward and holds 275 gal if that's full I can't get mine to plane either, even though with 100 gal in the tank I can hit 20 KTS Ballance is as important as total weight for getting over the hump.

[Pascal]

What was the performance like during survey? Did you loose some soeed or es she also topping at 15kts?

Don't just rely on indicators, look at the trim tabs to make sure they are fully extended. An alternative to extending the trim tabs that was mentioned here in the past is to add a spacer to increase the angle.

It's indeed all about balance. Different beast but the 84' Lazzara I now run doesn't even have any trim tab they tweaked the hull and balance so that she pops on plane with 3 degree bow rise and no tabs.

[saltshaker]

These boats need all they e got to get on plane and stay there. Im guessing with everything perfect they only run 15-16kts at cruise and 18-19kts WOT. Not sure they even plane well at all. There's a member here who did a lot of work to get his 56MY to perform better. I think he can cruise in the 18-19kt range and tops out around 22-23kts. I remember seeing pictures of it running fast and she still was pushing a bow wave.

[kjcampos]

rsmith our water tanks hold 350 gal. they are empty as i mentioned they are in the aft state room under the bed between the stringers and also one long one against the transom ....
Pascal yes she ran the same at survey like i said i never thought i would want to go up on plane ...what is this spacer you are talking about ...do you have a picture what does it cost?...
Jack i would Love to cruise at 15 knts when its needed but all i do is squat down and push a lot of water...you had asked before where do we sit at the water line on our boat.. we are now about a little over 3/4 fuel full and about 50 + - on holding tank empty water tanks with the 13' Boston Whaler tender up on top and we are sitting with our exhaust openings about 1" out of the water

[Pascal]

It's just a spacer, which can easily be made out of starboard placed between the cylinder and the tab or between the top of the cylinder and the hull. 1 to 2" thick would be a good start I guess I think it's easier to add on the tab instead of on the hull as the cylinder probably thru bolted to the transom and access will be difficult. I haven't looked into this yet but will when we install the cummins hopefully later this year

[SeaEric]

At 15 knots I think you may be technically on plane. It just may not level out like you would expect at a slightly higher speed.

[Boatsb]

I think that's still on the upward push. It's not on top but plowing hard trying to get on top.

[saltshaker]

I just went back and read your initial post again. I do think you are under propped and your issue is the engines aren't making full RPM. Your engines can seem to run flawlessly but aren't set right or you may have one cylinder that's low or not firing. You mentioned new injectors. More often than not there will be a few that don't perform
Properly. Your issues may be simple but you need to check the engines first. Can you tell if the throttle is advancing to full? You said you took an inch of pitch out with no change. That should have increased RPM as you are reducing the load on the engines. Send a PM to JLR. He had the same boat as you and may be able to offer some performance data. Pretty sure he regularly ran on plane.