36 Calvin Gear/Prop selection

fishmanfh

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Seeing if anyone has any real numbers on the 36 CB. I am doing a build this fall and getting ready to purchase engine/gear so it will be there as the hull/top come out this fall. The boat will be used to commercial/charter fish in florida and will have about 300 gallons fuel, 60 gallon water, head and full top.

I will be powering the boat with a Cummins QSL9, 405hp at 2100rpm. Trying to figure out if I would be better off with a 2:1 or a 1.75:1 gear ratio. I have some numbers, but really seeing if anyone has some real time data that might be helpful.

As of now, the 1.75:1 gear would need around a 28x27 4 blade and the 2:1 would need around a 28x32 4 blade.

Any thoughts or data would be greatly appreciated. thanks, John
 

petrel

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I guess it all depends on how fast you want to go and how much weight you need to carry. If you don't have far to go for charter fishing and it's more about hauling the freight, I'd think 2 to 1 and maybe even 30 inch diameter if you could swing it. Of course blade area could vary in 28 inch wheels to give you more bite too, so a 28" DQX w/ a 2 to 1 if you hadn't already figured on that. I know nothing about that particular hull or the engine, but I think you are on track w/ getting the shaft speed where it needs to be w/ a slower turning engine.
 

BillD

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Seeing if anyone has any real numbers on the 36 CB. I am doing a build this fall and getting ready to purchase engine/gear so it will be there as the hull/top come out this fall. The boat will be used to commercial/charter fish in florida and will have about 300 gallons fuel, 60 gallon water, head and full top.

I will be powering the boat with a Cummins QSL9, 405hp at 2100rpm. Trying to figure out if I would be better off with a 2:1 or a 1.75:1 gear ratio. I have some numbers, but really seeing if anyone has some real time data that might be helpful.

As of now, the 1.75:1 gear would need around a 28x27 4 blade and the 2:1 would need around a 28x32 4 blade.

Any thoughts or data would be greatly appreciated. thanks, John

John,

Send Tony @ Seaboard Marine an email ([email protected]) and ask him for his opinion. The QSL9 405 is his engine of choice in this size commercial build.
I don't think he has built a 36 Calvin Beal but he has a 38 WESMAC build going on right now that has the same engine and I "think" a 2:1 gear.

btw, Tony has around 40 QSL9's under his "watch" with many over 5,000 hours and some over 10,000 hrs.

The QSL9 is a great no frills commercial engine that you can pull a solid 400 hp cruise hp out of The engine also has solid low rpm torque for turning hydraulics etc.

FWIW, Bill D
 

petrel

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Bill D, 405 hp is not really the "cruise hp" if full power operation should be limited to an hour a day or something like that and the engine is 405 hp at WOT. Anyway, what is the cost/weight of that engine? Couldn't find the weight in the links I followed.
 

fishmanfh

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I just sent Tony an email for his thoughts. Many thanks and I will let you know what he says. I have heard nothing but great stuff about the engine and the longevity of it.
 

Cfood

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The QSL 405 is a "medium continuous" rated engine, 6 out of 10 hours at max rpm. the 330 is rated as "Heavy Duty" 8 out of 10 hours at max rpm. So you basically can run the 330 at 1800rpm darn near full time. The 330 would allow you to swing a bigger prop assuming you have the room, better cruising speed, but less top speed
 

petrel

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Yeah, but you could also run the 405 a couple hundred off the top.
 

MDI45

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I had a Wayne Beal 36 with a 420 Cat 507a 2 1/2 to one....28x28.....405 will not swing 30x30 with 2 to1 gear.......I would not go 1 3/4 to 1
 

Cfood

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If your you prop both engines to reach max RPM, and run both at 1800, the 330 will be more efficient given that you will be swinging a larger prop. All depends on the operators needs or requirements.
 

CaptDave

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Why don't you ask Stew for his opinion, I am sure he is laying uo the hull and top. Who is going to be the finisher, will it be someone in ME or you having done locally in FL? Love the CB hulls and wishing you the best of luck.

Dave
 

fishmanfh

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I have been asking around, but I don't think people are used to the 2100 rpm engine.

Trying to figure out if there was any real time data from someone that might be using this engine with a similar hull.

Prop calcs show a 2:1 requiring a 28x27 4 blade, or a 1.75:1 requiring a 28x32 4 blade.

Not really sure what the pros cons are for each. I have heard people say you want to stay close to square? Thanks for the inputs.
 

longislander89

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@cfood

Why would you be swinging a larger prop with the 330hp

Is it because of the torque curve?

Wouldn't you have a larger wheel on the 405hp but just be running it at a lower rpm?

Can someone please explain in detail the lower rpm motors and gear ratios and why they are more efficient. Are they faster or slower overall

Take a 400hp 3000rpm motor v the 400hp 2100 rpm motor.


Thanks in advance. Always enjoy learning more
 

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