Quickie for Dhadley

[fireman57]

Have older firberglass 14.5ft boat with 91 25hp johnny. Prop is 10x13 and I only turn around 4100 rpms. Smart tabs have helped with hole shot and planing but I just don't seem to get it out of the water like I would like. Might not ever. I know that I am underpowered as the boat is rated for a 50hp. Still looking for one. Concern is mainly for my engine. She's a sweety and I don't like lugging it like this. I was thinking of going to a 11x9 to bring my rpms up. I am guessing that it will get me about 5000. Is this right? Thanks for answering all these setup questions. You da man!

 

[JB]

Re: Quickie for Dhadley

It is sure worth a try, fireman. You might find that a 10" will get you into the power band pretty well.

 

[CATransplant]

Re: Quickie for Dhadley

A 10x11 might also work in that application. Check eBay. Lots of props available there, and sometimes for cheap.<br /><br />I'll bet your boat will perform a lot better if you can get that engine up to its rated RPMs.

 

[fireman57]

Re: Quickie for Dhadley

Thanks for the replies. The reason I was going to try the 11x9 is because I could get the 9 pitch. will a 10x11 (which is the steepest pitch I can find in a 10") give me the rpms I need? I'm not so much worried abou top end as I am lugging my baby. Been watching ebay but they bid them to within 10.00 of new. Rest assured that it will be purchased here. Doing price comparisons I have found that here is always withinten bucks of everywhere else and I will support this site for ten bucks.

 

[CATransplant]

Re: Quickie for Dhadley

Here's what I'm thinking: You have a 10x13 on your 25 hp motor on a 14.5' boat. I'm running that exact diameter and pitch on a 35hp motor on a boat that's the same size. It spins up fine, planes the boat at 25mph. This is a fiberglas trihull. It turns out to be the perfect prop for my setup, and I've got a few more hp than you do.<br /><br />The 10x11 will definitely give you more RPMs on the top end, hence more power. I don't know for sure if it will get your 25 up to rated RPMs, but it'll come a lot closer than the 13-pitch. It'll also improve your hole shot a bit.<br /><br />I'm guessing the 9-pitch will be a little to low a pitch for your combination, and will end up over-revving.<br /><br />The 11 will give you a boost. Whether it will be the optimum is another matter, but it will certainly help.<br /><br />BTW, have you tried different tilt settings with your current prop?

 

[Dhadley]

Re: Quickie for Dhadley

A lot depends on the brand prop also. A Turbo is going to bite harder than an E/J prop. <br /><br />Fireman57, send me an e-mail to dhadley50@aol.com I have an idea. Use "Iboats" as the subject so I'll see its not junk mail.

 

[fireman57]

Re: Quickie for Dhadley

CAT I don't have a jackplate on this boat but have tried every hole on the trim. I set my brother's 76 35hp evie up and he has the same length boat but about 10" wider beam. Doesn't sound like it's much more boat but it is more comfortable than mine. He is also running a 13" prop but his is shear pin. He has a spare but no markings on it. He doesn't get to his correct rpms either but he is only about 300 off. He will outdistance me by about 125-150 yds over a mile so I think I'm running about as good as I can (around 18-20 mph) with my current setup. Just don't want to hurt my engine by loading it up. Don't get me wrong I don't want to over rev it either.

 

[CATransplant]

Re: Quickie for Dhadley

Well, if you're that far down on RPM's you can do better with your boat. Dhadley will probably have a good idea for you. If you can get up to the design RPM's, I'll bet you can add a couple of MPH to your speed, and won't be lugging your motor. You may not go a lot faster, but the engine will be more comfortable.<br /><br />If you've tried all the trim positions, I'd guess you have about exhausted that option. Let us know what you try, and what you find out. If my old RDS-20 ever gives up the ghost, I'm probably going to go with a 25hp, so it will be useful info.

 

[Dhadley]

Re: Quickie for Dhadley

Fireman57, which 1991 25 do you have? The model number will tell.

 

[fireman57]

Re: Quickie for Dhadley

VJ25ELEID. 14 spline thru hub exhaust. 1991 long shaft.

 

[Dhadley]

Re: Quickie for Dhadley

OK, I was thinking of the other one. No matter. Have you tried raising the motor up slightly? I hate to see you drop pitch to gain rpm. I'd rather we work with the set up first. You might try putting a 1" spacer under the clamp bracket.

 

[fireman57]

Re: Quickie for Dhadley

Haven't yet but will try this weekend if the thunderstorms aren't too bad. Supposed to have them the next 6 days.

 

[Dhadley]

Re: Quickie for Dhadley

I hear ya. Same here.<br /><br />We're not that far off on rpm. I have a feeling that if we can get you close to 5K we'll be talking to your brother next.

 

[fireman57]

Re: Quickie for Dhadley

I'll also get my buddy with the digital camera over here and maybe I can post a pic.

 

[ross patti]

Re: Quickie for Dhadley

Hey fireman,<br /> sorry to drop into this thread,but could you please teach the old rosco how to post a pic ??. see you at outboard non repair .<br /> thanks.....

 

[fireman57]

Re: Quickie for Dhadley

Once my mate gets these pictures he will have to show me how to do it and I will be happy to pass it along. Gonna try to dodge a few storms and get out this arvo and try Dhadley's suggestion. Got it raised an inch. I'll let you know.

 

[Dhadley]

Re: Quickie for Dhadley

One more thought -- if your prop is worn it may vent in a tight turn. Dont worry about that if it does. We're only interested, at this point, to see how it reacts to X dimension increases. <br /><br />I have a feeling the prop is in good shape so its probably not a concern.

 

[fireman57]

Re: Quickie for Dhadley

Prop is not in the best of shape. A rock or two here, log there, 11yrs of my hard use. Nick or two and pretty decent wear on the edges. I am going to replace and that is why I wondered which way to go. The old one was fine on my light aluminum flat bottom but this heavy fiberglass vbottom is a different animal to push.

 

[Dhadley]

Re: Quickie for Dhadley

OK, thats fine. Lets test with it anyway. We'll just keep that in mind. If it responds to the height thats all we need to know for now. The secret is -- 1 change at a time.

 

[fireman57]

Re: Quickie for Dhadley

Took her out tonight with a normal load which is me at 175 and another at 225. Only picked up 100rpms. I know the prop is not in the best of shape. Heading out for fishing we ran okay but once I filled the live well (ten gallons) it was tough to get on plane. Went through the trim holes and ended up again at the same one with a poor hole shot but the same top end. When I say a poor hole shot I mean it doesn't raise up much it just takes a while to get to plane with the underpower. I may need to adjust my trim tabs down about 5 degrees for the hole shot but it takes forever to start to get above the water. AV plate is actually about an inch above the water while I am on plane and water pump still works fine but intake is just barely in the water now. I have about another 1/2 inch I can raise it but then would be out of room to run the clamps down on the transom. Running around 4200-4300 WFO on plane now.