Just finished my surface drive and I went test it yesterday and I'm only getting 8 mph. My ratio is 1.375:1. I'm running a 9x6 prop. The boat is 1436 and the motoe is 13hp. I do have a 10x8 prop. Do you think this is right or do I need to put the bigger prop on it? Will it make a difference?

What is your rpm?

are you using a surface drive prop or a longtail prop? you prolly wont get more than 12mph at most with everything perfect....

not sure on the rpm, waiting on tach in mail. the 9x6 is a longtail prop. i had it on a longtail and i was pullin 15-17mph. maybe my gearing is screwed up?

Prop has a lot to do with it.

Get a surface drive prop

:/ and I think the 10x8 I have is a longtail... its the one from hill marine any way to tell if its a true sd prop? Thanks for the input guys!

Google that shit, props look totally different

So like a 9x9 will put me In good standings?

Im running a tricked out 13 hp. 36top 44 bott = 1.22

Dixie Mud Motor 1442 alumacraft.

9x9 max 24 mph alone. Slips with load

9x10 custom re-pitch & cup same top speed but slips bad under load

10x6 is the best prop for my boat under all loads. 6% slip. rpms below 3700.

good luck.

24 mph? That's outstanding! I'm close to the same gears. I have 32top and 44 bottom. But as mentioned nowhere near those speeds!

Good info - are they SD props or LT ???

24mph is awesome with only a 13hp motor !

He said above he had a 10x8 - do you think he could turn
it with his lower gearing ???

I think my 10x8 is a lt prop.... and my 9x6 prop came off a lt. What rpms should my motor be seeing? I saw a calculation a while back whatever your rpms on motor were you could figure out what the prop was spinning. Don't remember what it was though. I really appreciate the info guys

I would think 3800-4300 rpm that's what all my motors ran

If thats the case it should have no problem spinning the prop I think the prop according to mudbuddys site is rated for 3800-4000.... unless the prop can be overspun? What's that about?

Theoretically speaking.... damn and I'm half of that. I guess ima have to wait on thay damn tach and go from there thanks gigafowl!

When I hook my tach up do I run that out of the water? Or do I get a reading in the water?

Will I be able to tell out of water if ill be able to turn a 10x8?

I don't think so. He's saying to make sure your motor is running max rpms out of water. To make sure your gov is set right.

Ok and the norm would be 3800-4200? And if not remove the governor?

Run ur motor on the trailer and see what u can turn up.
If u don't turn up 4200 that's part of ur problem, adjust so that u do.

Then launch ur rig and see what u r turning up. Wot
U wanna b turning up bout 38 39

If ur not turning that high ur not turning ur prop
If u over turning u need a bigger prop r pitch

The goal u r trying to achieve is turning the biggest prop ur motor can turn
There for pushing more water
Running faster

Thanks makes sence now.

Ok got all my throttle figured out. Removed the governor and hooked up the tach, 5200 comftorable and it could go higher but prolly not safe for motor. What y'all figure it would turn in the water?

5200? And you're comfortable with that?

Not particularly, thats what I got it to before. I shut it off. Question I was trying to get to was is it enough to spin a 10x8

Did you understand that the governor setting was to LIMIT rpms
to NO MORE THAN 4200 rpm ???

This protects the motor when it pops out of water unexpectedly....

Sometimes when it is set too LOW it limits at below 3500 - and that
is why guys told you to check your out of water rpms.... You need
to get that thing set right or you will loose the motor to excess rpms
like the 5200 rpms you just turned....

When you are properly setup with the right prop you will be turning
between 3500 and 4000 - but no one will be able to tell you anything
from what you have posted thus far too many variables....

Now that you have a tach - get out and water test it to find that
proper setup - you can post up info with rpms and speeds on different
props and then get more input....

Thanks giga ill put it back in amd see where I'm at and adjust accordingly.

You better swap you life jacket out for a Kevlar vest to help protect you when the fly wheel comes apart. 5200 is WAY TOO HIGH for that motor. Running the motor out of the water won't do you any good. All of you tuning needs to be done in the water.

Ok I got it set on the bench a lil over 4200. But if I meed more in the water I can get it. Is this safer?

U don't want more than that, ur motor will blow.
Ur motor is now set right. At this point everything else is prop. Put it n the water wot and see what Rpms u turn up.