Not allowed full speed with 8v71’s whilst surveying

[rsmith]

1968 50 notice the square windows that started in 66 or 67

[Photolomy]

But will they stay on plane at 1800-1900?

No. I wouldn't have made my statement if she could plane at 1800 rpm, that is 75% of max. There are only two speeds with a 53, displacement and plane, unless you have naturals and then there is only one speed. But it is nice that if you have to get somewhere a bit quicker (weather etc.) that you can open her up and plane.

[krush]

RTFM 200rpm off full throttle

Yes, be a diesel god and read the manual. All the information is in there. Early detroits like the naturals don't burn enough fuel to hurt themselves....run them on the pins all day long LOL. But then they added fancy turbos and coolers and upping injector size.

I don't really understand all the debate anyway....1800rpm gets me 19 knots

[racclarkson@gmail.com]

RTFM 200rpm off full throttle

WNSAC if you’re able.

[Pascal]

No. I wouldn't have made my statement if she could plane at 1800 rpm, that is 75% of max. There are only two speeds with a 53, displacement and plane, unless you have naturals and then there is only one speed. But it is nice that if you have to get somewhere a bit quicker (weather etc.) that you can open her up and plane.

There are only two speeds with any planning hull, this is not an issue limited to the 53. Every boat I ve run with flow meter will show about 75% more fuel for an extra knot about hull speed. Problem is that with the 53 and 8V71TIs, there is only one planning cruise speed: whatever the boat will do at 2000

[SKYCHENEY]

But will they stay on plane at 1800-1900?

They did when new before all of the additional weight.

And I run mine at 2150rpm at cruise. They like it there. Its not an issue. We had Detroits in all kinds of trucks and construction equipment for years and our mechanics always said that those engines were meant to be run. They told all of the operators to put the pedal to the floor. Don't baby them or lug them. Two-strokes need air to run well. Let them breathe.

All Hatts were planing hulls except the 48MY which was semi-displacement and the LRC's which are displacement hulls.

[Boatsb]

Sky there is no proof that what you say is true. Please post pictures and other documentation as soon as possible. If not your statements will be summarily dismissed as bragging and puffery.

53 motoryachts should never be run on plane or over 1950 RPM's. It's just not natural.

[jim rosenthal]

The engine survey should do a no load to 2450 better have a defib on standby for that guy.

For the engines or the owner?

[jim rosenthal]

Agree with Sky. I also think that if we all had pyrometers and boost gauges on our engines we would think differently about where to run them at cruise.

[jim rosenthal]

Also FWIW I was on MikeP's boat, Brigadoon, several times for trial runs, and she would do better than 17 knots, planing, at WOT (8-71 TIs, 435hp/side)

As some of you know, MikeP spent years building racing engines and is the most accomplished mechanic I've ever met. He usually did brief full-power runs after the bottom was painted and the boat went back in the water to check that everything was working as it should.