prop and motor heigth

[t_brown1986]

Re: prop and motor heigth

What do you mean my set up is way off??? Max out how?? Im lost...

 

[Senderofan]

Re: prop and motor heigth

What do you mean my set up is way off??? Max out how?? Im lost...

Dhadley is trying to help make sure the motor set up is correct...and save you some money and time by not buying the wrong prop. The motor has to be be mounted at the correct height for your particular boat for the engine to perform at its best. If the motor is mounted too low...too much of the lower unit is dragging in the water. That will lug the motor and drive you crazy trying to figure out how to get better hole shot, top speed and fuel efficiency. If you were getting 4,000 rpm at WOT...that's what Dhadley was reffering to when he said your set up is way off...your rpm's are too low. I think he's trying to recommend that you need to raise your motor ( Mounting height )..whether you can do that with the existing holes...or need to install a jack plate....I guess he could make recommendations if you posted some pictures.

The Cav. plate...or AV plate needs to be riding at the surface of the water or slightly above when you are up on plane. The plate is the wide horizontal thin metal deal that is just above the prop.

I'm zeroing in on a new prop for my re-power...so these are the things I've learned from guys like Dhadley and others. I've got my new motor mounted at the proper height...it makes a Huge difference on my rig. It will really pay to make sure your motor is mounted at the proper height and make sure the motor is running up to its potential before you start investing in props.

This mounting height, x-dimension, stuff takes a while to digest. Take the info. from these guys...learn as much as you can...then apply it to your particular boat / motor. I think you'll be very happy with the results. The guys here have been there...done that...they'll save you time, frustration and $$$.

Good Luck,

Wayne

 

[t_brown1986]

Re: prop and motor heigth

ok i have a jack plate i think. its a metal thing the motor is mounted on and it says hi jack i think... anyway should the cavitation thingy be even/above water when on plane with the trim all the way down?? Where should trim be when this plate is level?? and all I have to do is adjust the big long bols on each side right??? were gettin up at 4am to be on water bass fishing at day break.. it isnt gonna hurt to run it like it is tomorrow is it??? and reason i wann change prop is when i gun it it spikes rpms before it grabs then grabs and starts to plane....

 

[Senderofan]

Re: prop and motor heigth

On my boat...my motor is trimmed in...I get on plane and my Cav. plate is skimming the top of the water. High performance hulls...I think your plate can have air under it...as long as you have the right kind of prop. I trim my motor out watching rpm's and speed. This maximizes the efficiency of my set up...I'm looking for fuel economy as well as decent performance.

I've got a large aluminum fish and ski....so take my experiences as a generalization. My previous motor, a 150 hp, was mounted too low...now...with a 175 mounted at the right height..I'm getting 50% better fuel economy ( unbelievable...but they'll also be turning about the same pitched props)...doing our little local lake running.....granted it also is a DI 2 stroke versus a carbed one.

Not sure the spiking of the rpm's is a good thing. I think your ventilating / blowing out. Perhaps someone mounted it too high to run a high pitched prop?

I'm certainly no expert...the experts will be able to give you more advice. I just know it's critical to get the motor set up properly...or you have one big headache trying to maximize performance / efficiency out of your boat.

Wayne

 

[t_brown1986]

Re: prop and motor heigth

not sure but i will look tomorrow and see where I am setting... and yeah my fuel sucks right now.. and i only have 12 gallons.. so yeah.. but im off to bed ill touch in tomorrow and let you know where it sets... thanks alot.. you made it easy to understand!

 

[Senderofan]

Re: prop and motor heigth

not sure but i will look tomorrow and see where I am setting... and yeah my fuel sucks right now.. and i only have 12 gallons.. so yeah.. but im off to bed ill touch in tomorrow and let you know where it sets... thanks alot.. you made it easy to understand!

No problem....I was there not too long ago. It's a little overwhelming..but the guys here are trying to help you...we just need to get up to speed with some of the terms and ideas behind what they are saying.

Have a great day on the water...wish I could get out...to cold and rainy.

Wayne

 

[t_brown1986]

Re: prop and motor heigth

thing ran good all day today.. just hole shot sucks... think a 19 or 20 pitch would do good?? And from where and what name do you guys like??

 

[Dhadley]

Re: prop and motor heigth

Did you raise the motor any? If so, what's the top rpm now?

 

[t_brown1986]

Re: prop and motor heigth

no i didnt have to.. it ran about 5k with the best trim spot we could find and i crawled back and looked at cavitation plate and it was riding on surface of water... this is what i was told it needs to do.. not sure on speed cause speedo still no work.. it works from where it plugs to foot to speedo but where it goes inside of foot past that im lost..

 

[Dhadley]

Re: prop and motor heigth

Your motor is too low. Don't worry about where the AV plate is when you're on plane. You need more top rpm and to improve holeshot. Raise the motor and retest.

 

[Senderofan]

Re: prop and motor heigth

I'm not sure on the rpm spec's of your particular motor...but I think you probably can stand a few hundred more rpm on the top end. I think that would also give you a lot better holeshot....because you're going to go down on pitch...if your motor height is correct...which it sounds like you're in the ballpark.

On my old motor...I went from a 21 pitch aluminum Merc. prop. to a 19 pitch stainless. The motor gained 250-300 rpm on the top end and I gained some on the top speed mph....more importantly...the holeshot was night and day different.

As far as what brand prop to go with...the experts here can steer you to one that will most certainly benefit your rig.

Wayne

 

[t_brown1986]

Re: prop and motor heigth

you guys keep saying more rpms.. how can that be possible if my plate is already even/above water?? I mean the prop is the same a HUGE 22pitch.... stainless.. dont see how i can make it turn faster?

 

[t_brown1986]

Re: prop and motor heigth

also i looked online and it shows my recomended wot rpms to be 4500-5200...

 

[t_brown1986]

Re: prop and motor heigth

so how far would yo guys start moving it up.. like 3 inches at a time??? or what?

 

[Dhadley]

Re: prop and motor heigth

Since you have a jackplate raising the motor is easy. I'd start by moving it up about an inch at a time and watch the water pressure compared to your baseline (what it is now). Once it's up then test and see how the rig responds to that single change. If it's favorable, go up some more and retest. Once you get to the optimum height for that prop you have maxed out the set up for that prop on your boat. Then you can tell where you are and where you need to go.

 

[junior1113]

Re: prop and motor heigth

error

 

[t_brown1986]

Re: prop and motor heigth

error??? havent made it back out we just had our little girl so im setting in the hospital...