Prop question ,any help PLEASE

[joeyd50]

Hi guys, I have a 1986 Skeeter 18.5 foot bass boat, I have a 1975 85 HP Johnson outboard on it, any ideas on what prop I should have? or what would be a good prop to start with? Im sure the boat is about 1500 lbs. this is the first outboard I have had on this boat.<br /> Thanks<br /> Joe

 

[tommays]

Re: Prop question ,any help PLEASE

you need to start somewere so tell them what you have now RPM speed ect<br /><br /><br />tommays

 

[joeyd50]

Re: Prop question ,any help PLEASE

I havent had the motor running yet, I just put in on the boat, and the prop that's on it is trash, Im trying to find a starting point on selecting the best prop. Do you guys think I should just go to a Johnson dealer? I have a dealer close by, but I havent dealt with them in about 20 years. Is there any web site that might help? I was hoping someone here had a similar boat and motor.<br /> Thanks<br /> Joe

 

[Dhadley]

Re: Prop question ,any help PLEASE

Is this a pad bottom hull? Does it have a step? Is the motor mounted on a jackplate or to the transom? Does it have a low water pick up nosecone?

 

[POORBOY]

Re: Prop question ,any help PLEASE

Go to Google search engine type in Michigan wheel propellers. they have a good tech section which will help you select the proper propeller. At least they really helped me. Good luck.

 

[walleyehed]

Re: Prop question ,any help PLEASE

This is a good example of why a prop finder can be a waste of time & money...the prop finder doesn't acount for engine mounting heigth, set-back, lower unit type, or hull style.<br />The best Prop "locator" I've found yet, is Dhadley....answer his questions and he'll put ya as close as can be...

 

[ron7000]

Re: Prop question ,any help PLEASE

i just did a spreadsheet for another reason, but you should know the average top speed the boat should do and your gearcase ratio, from there figure out the pitch. Will get you close if you have no idea.<br />For a bass boat I would think at least 40mph at wide open at 5000 rpm.<br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=013313

 

[joeyd50]

Re: Prop question ,any help PLEASE

Dhadley,I dont know what a pad bottom is,I dont know what you mean by a step,it is mounted on the transom,I dont know what a low water pick up nosecone is. The transom is 20" and the shaft is 20",I feel like a real a$$, I dont know what your talking about.<br /> Joe

 

[Silvertip]

Re: Prop question ,any help PLEASE

I just run some numbers in a prop calculator. The correct prop should allow the engine to rev 5500 - 6000 rpm at wide open throttle. A prop with too little pitch causes over reving. A prop with too much pitch causes lugging. So -- assuming wide open throttle rpm of 6000 rpm, a gearcase ratio of 2.0:1, 10% prop slip, and guessing at a 45 MPH top speed, the calculator says 17.6 inches of pitch. I would look for a used 17 inch "cupped" prop on E-bay, at any on-line store, or your local dealer. If that prop is on the money, great. If not, you should have a good starting point.

 

[Dhadley]

Re: Prop question ,any help PLEASE

No problem Joe -- a pad bottom is a hull that looks like it has a ski on the keel. Where the V comes down on each side it will come to a V or a U shape. If it comes down and goes to a distinct flat surface, thats the pad. The pad is usually about 6" or so wide on a boat that size. It can be as small as 4 1/4". Like I said, it'll look like a ski or a flat board on the bottom.<br /><br />The step is at the rear of the keel. If a boat has a pad it usually has a step or notched transom. The pad or keel will come back and end before it gets to the transom. The hull then goes up about 6"-8" and then goes back. From the side it looks kinda like a Z. The keel goes back, then up then back again.<br /><br />The nosecone low water pick up is an aftermarket "bullet" over the existing lower unit. The front or nose of the gearcase is extended and the water inlets are at the bottom of the nosecone. The stock water inlets on the side of the gearcase will, most likely, be covered up.<br /><br />Since you said the transome is 20" I'd bet we dont have a step. Without a step I doubt theres a pad. Lots of bass boats have both. Thats what helps make them as fast as they can be.<br /><br />I would guess that Smoke has the right idea. A 17 might be a good starting point. The 85 has a small bore so it doesnt have the torque that a 115 has. We may be looking at a 15" prop, depending on the normal load. Either would be a good starting point. <br /><br />Are you thinking stainless steel or aluminum?

 

[Ron G]

Re: Prop question ,any help PLEASE

The skeeter is a pad and should have a step,from all the ones ive seen.

 

[joeyd50]

Re: Prop question ,any help PLEASE

I got the boat out yesterday 7/29/07, first time with the 85HP on it, ran real good, I thought it would go faster, got up to 32.6 MPH according to the GPS, RPM was right at 5500 with a 13X19 prop, so I guess that's top speed.
Joe