A need for speed

[Wild Bill]

I am the proud owner of a 1977 37-c. She is equipped with 6-71n's turning 24x24 wheels. I would like to boost her a couple of knots without screwing with the engines (my girls are happy the way they are).
Any suggestions?

 

[surfdancer45]

With N's you are not going to anywhere very fast but you will be very comfortable. The only things you can do to max the speed is to reduce boat weight (be ruthless in keeping "stuff" on board to a minimum), keep the engines tuned and keep the bottom clean. If you want speed out of this hull you are looking at a repower with modern lightweight diesels. Good luck with your 37. Bob

 

[Jaxfishgyd]

If speed is what you want, you bought the wrong boat.
The N's are NOT speed demons but will last you forever if taken care of. Plus with the price of fuel these days, you will realize how good you have it when you pull up to the fuel dock along side a boat with turbos and see who's bill is a lot less.

 

[Wild Bill]

With N's you are not going to anywhere very fast but you will be very comfortable. The only things you can do to max the speed is to reduce boat weight (be ruthless in keeping "stuff" on board to a minimum), keep the engines tuned and keep the bottom clean. If you want speed out of this hull you are looking at a repower with modern lightweight diesels. Good luck with your 37. Bob

Any ideas on changing props. I am currently running 24x24 four blades. I wonder what 24x27 three blades would do?
Bob

 

[Trojan]

Unless your loaded heavy. It sounds like your under pitched. I am 43ft with J&Ts 6-71N and I twist 4 blades 24 X 27 at WOT 2650 RPM.



Bill

 

[SKYCHENEY]

Which gears? We all talk about what props and hp and rpm, but to really compare, you need to know how fast they are turning at the prop. If one of you has 2 to 1 reduction and another has 1.5 to one, then there is a BIG difference.

 

[Trojan]

I just put that in there for some though. A 43 is different than a 37. My gears are 1.5 to 1.. The 37 will never be a speed boat, But he also never stated how fast it is now or the WOT. So any comments made here won't do a whole lot of good. We need facts!



BILL

 

[Wild Bill]

I just put that in there for some though. A 43 is different than a 37. My gears are 1.5 to 1.. The 37 will never be a speed boat, But he also never stated how fast it is now or the WOT. So any comments made here won't do a whole lot of good. We need facts!



BILL

You're right, I forgot facts.
Facts is:
6-71n's
24x24 wheels
1.5 gears
wot 2400 ( I'm sure the wheels are dirty)
15kts at wot

WB

 

[REBrueckner]

Sorry to bear bad news. If you figure out a solution, you will be ready to become a billionaire via that discovery!!! No way no how you can gain two knots if your already turning about rated top RPM. Adding 2 knots on top of 15 is a pipe dream; that's a 13% increase in speed. Relax and enjoy your dependable babies.

Gaining two knots likely requires another 20% or 25% increase in HP (just a guess)...see "Expected Speed increase with Larger Engines" thread on this list and you can calculate about what HP would take for your boat...that will put it in perspective.

You might edge out a bit more speed by: traveling with any favorable currents; keeping your bottom clean and running gear clean; having your props computer reconditioned, keep gear,water and fuel to a minimum, remove flybridge,tower,outriggers, even salon, if any, to cut wind drag; remove doors and replace with curtains (like Huckins); remove stainless cleats and replace with aluminum. You should also go on a serious diet as should any guests or family members to keep your weight under 100 lbs apiece.

 

[Bob Bradley]

If you do decide to swap wheels, drop me an email. I might be interested in the ones you have now.

 

[krazy8]

1977 37-c. Call Tom Slane then Cut off your Keel

 

[Trojan]

Your engines are most-likely J&Ts. There WOT is supposed to be 2650 RPM. Not 2400. My 43 runs 20 MPH WOT and cruises at 18 MPH. I think you need some prop work. I turn 24 X 26 wheels.



BILL

 

[Wild Bill]

Your engines are most-likely J&Ts. There WOT is supposed to be 2650 RPM. Not 2400. My 43 runs 20 MPH WOT and cruises at 18 MPH. I think you need some prop work. I turn 24 X 26 wheels.



BILL

Thanks for the info. I was not sure what WOT was supposed to be. I do believe mine are J&T's.
I think I have a breathing problem, lately they are only reaching about 2325 rpm. Fuel filters are new. Air filters are not, but will be. I am currently moving at 12kts at 2200 with a full load of 8 people and full fuel and water. All I want is a 16kt cruise. I think hat is attainable.

Thanks,
Wild Bill