37c repower+ performance

[37hatterascal]

I HAVE A 1978 37C WITH 310 HP.DETROITS TOP SPEED IS 17 TO 18 KTS. I AM CONSIDERING 3126 CATS RATED AT 420 HP. DOES ANYONE HAVE ANY INFO AS FAR AS PERFORMANCE ON THE HIGHER HP AND ON THE 310 DETROITS. THANKING YOU IN ADVANCE

JIM

[Scott Mather]

Our 1978 37 Hat has 310 Hp J&T's
Cruise speed is 16 to 17 knots (GPS) 2250 RPM
Top speed is 21 to 22 Knots (GPS) 2400/2450 RPM
Cruise numbers in deep water
Cruises at 18.5 knots in 15 ft. or less water.
Has original spec. 4 blade wheels.
Also has hard top, half tower and out riggers
Also has stripped, de-blistered, painted bottom.
Had boat weighed in lift 30,000 lbs. with half fuel.

Have one rebuilt engine, (valve Job, sleeves, pistons bearings) Expect another knot after other rebuild.

[aah924]

I would be very careful going with that much HP. There is a boat for sale, on yachtworld, in Chas, SC, with that same power. The boat is nice; however, I have heard that there is too much HP for that boat. The hull isn't designed for that type of speed. I have a '72, 36' with Cummins 370B Diamond Series engines and I cruise at 25-26 knots, with no problem. I have spoken with someone who said that the cat HP was overkill and makes the boat skate alot.

This is just what I've heard about that much HP.

[divernc]

1980 37C with J+T 671TA 390 HP with 800 hours. Clean bottom, running gear, soft top, no riggers. 1800rpm is 17k, 2100rpm is 21.5k, 2400rpm is 24.7k. GPS measured in 40' of water. No handling issues.

[jim rosenthal]

They are not the same boat. The 37 Hatteras is a much heavier, beamier boat with a far less efficient hull for speed but a better ride. This is why the diesel option for that boat was a 6-71. The 3126 CATs are too light an engine for that boat regardless of how much power they develop on paper. You would be better off with 3176 CATs or Cummins M11s. The 6-71 is a large heavy engine; the 3126 is maybe half or 60% of the weight of the 6-71. Interestingly, I think some 37 convertibles were powered with GAS engines...talk about slow and using a lot of fuel.
Rebuilt 3176s are available with factory warranty from Alban and some other CAT dealers...theywould be a good choice. The boat would be faster, but I don't know how much speed is in that hull. It is quite different than its predecessor, the old 36 convertible which really will go fast with the right power.

[Scott Mather]

I have seen 37's for sale with the 485 HP 671's
Some one should have performance numbers on these.

[Nick]

We have the 450 J&T. The cruise at 2050 RPM is 19-20 knots. At 2100, cruise is 21 and top end is 25 kts.

Bottom is clean and speeds at 3/4 fuel load.

[kdoxie]

I am looking for stats on repowering a 37. I now how 6 71 N's and cruise at 14k. I have been told that 3208's would be a good option for this boat. Anyone with 3208's at 370hp? How about Volvo?