senza 210 prop help

[crazygn]

Need help with a new prop size. Heres a run down, 1989 larson senza 210 with a alpha 1.5 drive. Chevy 350 , heads , intake and comp 268 cam motor. Engine runs around 4200-4400 rpm and 54-55 mph on gps. The prop is a ss mich 14.25x21 .

Iam looking for more top speed and think maybe a 19 might help me get over the edge and more in the power band. What band and size do you guys think. And should i stay with a 14.25 or go smaller

thanks guys for any help

 

[Pete104]

Re: senza 210 prop help

A 19" will get rpm your after. But go Mercury! Stay away from after market. Aluminum or stainless.

 

[crazygn]

Re: senza 210 prop help

really, what props do they make, any better then the others and what do you think about the Dia, stay with the 14.25 or go to a 13 or so

 

[Pete104]

Re: senza 210 prop help

I would stay with 14 1/4". Others will argue, go with a 4 blade. Your hull is "not" a fast hull. There wasn't much research done around that vintage. Talk to a prop guy in your area & see what he says. They will probably let you try them.

 

[crazygn]

Re: senza 210 prop help

I thought i was reading that a 4 blade will slow the top end up, is that true or no

 

[craze1cars]

Re: senza 210 prop help

Most 4 blades are not considered max speed props...but a few are.

You mention you are trying to get more into the powerband of your engine, but you do not provide us an RPM target. What exactly is the actual peak HP RPM your engine combo?

When you are at your current max speed, what kind of angle is the bottom of your boat contacting the water? This could probably only be observed from another boat alongside...or video.

Getting max speed is all about minimizing contact surface area. Do you currently need to lift the bow higher to minimize the contact patch, or would your boat benefit more from lifting the stern higher? This tells you whether you need to shop for a stern lifting prop or a bow lifting prop...buy the wrong style because you don't know whether you want bow or stern left, and you will end up going the wrong direction in speed...

 

[crazygn]

Re: senza 210 prop help

thanks for the info. The cam says peak is 5200 so i would think if iam at 4200 iam losing a good bit of HP. I'll see if i can find out a way to see what part of the boat needs to lift. It feels like the back would need to come up but thats just by feel.

 

[crazygn]

Re: senza 210 prop help

Also guys my trim tab are not working right not and they sit a hair over flat , do you think this will slow me up. What iam saying is will the boat go faster if i could put the trim tabs down some to try to lift the back out of the water