Need Faster Hole Shot

[patenglish]

My hole shot is horrible, but my WOT is great. I have a Champion 15'6" with an Evinrude 90 V4. Recommended RPM at WOT is 4500-5500. I am running at 5200 WOT. My present prop is a Raker 3.5 x 18. If I change to aluminum in the same size will it affect my RPM's on WOT?

 

[scotty c]

Re: Need Faster Hole Shot

try vent holes in the prop...<br />there are threads in this forum on how<br />to drill your prop

 

[rg33]

Re: Need Faster Hole Shot

I believe your rpm's will increase with aluminum because of prop blade flex. Is this the correct prop in diameter and pitch for the motor? If so, an increase in prop pitch may help. Check this site for props for your motor with the suggested pitch(es).

 

[roscoe]

Re: Need Faster Hole Shot

""My present prop is a Raker 3.5 x 18.""<br /><br />Did you mean a 13.5 x 18p ??<br /><br />Dropping down to a 17p should increase your rpm to 5400.<br />And switching to aluminum another 100 or so.<br />That would put you at 5500 wot rpm.<br />Should help with the holeshot.<br />Top speed should be about the same as the lower pitch prop is made up for by turning more rpm.<br /><br />Personally, after checking to make sure my engine is mounted at the correct height, I would get a 15p or 16p prop. It will help your holeshot even more, and top speed will only drop a little if at all. You rude would like to run at a few more rpm anyways.

 

[walleyehed]

Re: Need Faster Hole Shot

Before changing props, lets look at engine mounting heigth.<br />Is your engine setting "on" the transom or is it up some?? which holes are the top bolts in??

 

[umblecumbuz]

Re: Need Faster Hole Shot

Kenny:Before changing props, lets look at engine mounting heigth.

What Kenny says ...<br /><br />If you're happy with the way the motor runs at WOt, then you've proved that your pitch is about right.<br />Other issues may be affecting your hole shot. Always best to go through everything before just jumping on props as the culprit.<br /><br />Does the motor spin up freely when you're trying to get out of the hole? If not, drilling might help.<br /><br />Where is the weight in your boat? Can you move some forward? This can help holeshot.<br /><br />Where is the AV plate in relation to your keel? Can it be raised while still keeping prop grip and water pressure? An AV plate at or just above keel level keeps the minimum lower unit resistance in the water.<br /><br />Do you have a foil or trim tabs? If not, have you tried them?<br /><br />Is the motor itself in good shape and does it generally run well with no 'bogging' issues?<br /><br />When you can tick all the boxes, then go for the prop if needed.

 

[patenglish]

Re: Need Faster Hole Shot

Originally posted by walleyehed:<br /> Before changing props, lets look at engine mounting heigth.<br />Is your engine setting "on" the transom or is it up some?? which holes are the top bolts in??

 

[patenglish]

Re: Need Faster Hole Shot

It is raised 1.5" above the transom.

 

[walleyehed]

Re: Need Faster Hole Shot

ok, that means you're in the third set of holes.<br />If you don't have any ventilation issues, I'd raise it another hole and test.

 

[patenglish]

Re: Need Faster Hole Shot

Originally posted by walleyehed:<br /> ok, that means you're in the third set of holes.<br />If you don't have any ventilation issues, I'd raise it another hole and test.

 

[patenglish]

Re: Need Faster Hole Shot

The AV plate is 1.5" above the bottom of the keel. My prop was vented from the factory. Please explain what you mean by ventilation problems.<br /><br />On another topic your mentiond that 5200 RPM was lugging. Do you think I need to change to a 17p before changing the height?

 

[phatmanmike]

Re: Need Faster Hole Shot

vent holes are easy and free, try those first!

 

[patenglish]

Re: Need Faster Hole Shot

Originally posted by myoutboards:<br /> vent holes are easy and free, try those first!

 

[patenglish]

Re: Need Faster Hole Shot

As I said in my last post, prop was vented from factory.

 

[roscoe]

Re: Need Faster Hole Shot

By ventilation problems, they mean the prop will blow out in turns. You would know if you were ventilating (sucking air into the prop) as you would lose power and the engine would rev up.<br /><br />Correct engine height is as high as you can go without ventilating. So you raise the motor one hole at a time untill you start to ventilate, then lower the motor down one hole.<br /><br />After correct height is determined, (and your rpm will change when you do this) then you can change props to get your rpm in order and improve holeshot, if needed.

 

[Ron G]

Re: Need Faster Hole Shot

I think what they are saying is that the setup has to be right first then the prop.no need in spending money until you got the max out of the setup.

 

[umblecumbuz]

Re: Need Faster Hole Shot

And just adding to what Roscoe has said ...<br /><br />Your prop will also vent if you're butting into a short, steep swell and your motor's too high. The prop spins freely, the motor revs higher, and you lose speed.<br /><br />When trying for correct height, watch out not just for ventilating, but also for cooling water pressure. You can lose pressure if the motor's set too high on the transom.

 

[patenglish]

Re: Need Faster Hole Shot

I would need a crane to raise the engine or take it to a boat shop and pay them to do it. I can only raise it one more hole and it will be as high as it will go. Seems like a prop change would be a lot cheaper and easier, especially if I go to aluminum.

 

[umblecumbuz]

Re: Need Faster Hole Shot

No crane needed! No boat shop needed!<br /><br />Chock your trailer wheels. Put a trolley jack under your skeg, with a block of wood in between. Loosen the bolts (remove top bolts) and gently jack motor till holes line up. <br /><br />If the hydraulic trim tends to swing the motor out while you're jacking, then tie a line around the leg, feed it under the boat, tighten it and secure it to the trailer winch leg.<br /><br />It's a fairly common method of adjusting motor height on a transom. When you've done it once, you'll see how easy it is.

 

[shep70057]

Re: Need Faster Hole Shot

If you don't have a trolley jack, you can use the jack on your boat trailer and place the piece of wood under the skeg. You can raise/lower the front of your boat which will in turn raise/lower your motor if the bolts are loose.