I need better low end

[SteveDavis]

Hi everyone, just an fyi, I "have the case of the Monday's."

Anyhow, I want/need my 17.5' open bow Crestliner to have better low end. It takes a while to plane out. This winter I plan on cleaning my carb and the realated parts. But, this boat has been in the family ever since it was new in '86 and I know it never had a great hole shot. I am running a 4.3L GM engine with an OMC Cobra outdrive. Attached to that is a 3 blade 14.5x19 alluminum prop. I have thought of putting smart tabs on but I think I may decide on a prop for the ease of installation, if I can get some good advice. Currently my boat will top out @ around 55mph and 4600rpm (aprx, which is the manufactures recomended rpm). My top end is not huge, unless it dips bellow 40, but I would love to have more low end. Mainly because I would like to be able to pull skiers more easily and/or cruise easier. What do you all suggest? Change prop? If so to what? Just add smart tabs? Or maybe both. Can't wait to hear your thoughts.

Thank you!
Steve

 

[Maclin]

Re: I need better low end

Just my opinion........Seems like a 4.3 in a 17.5 boat should be plenty of power for what you want to do with the prop you have now. The prop you have sounds ideal based on the numbers you gave. Anything lower than your 19 pitch will cause an over-rev situation. Your post wording sounds like you suspect the engine needs some tuning work, so if you have some engine tuning issues my advice is to tune it up now. Switching props is not a good substitution for a much needed tuneup.

 

[SteveDavis]

Re: I need better low end

I want to tune it up, just because I think it is time, not because it really needs it. Or at least I can't tell it needs it. I tried to explain that it has always been slow to plane or slow off the hole shot. True, it most likely is slower now than when it was new, but not by much. So with that said, would a different prop be good? From what you are saying I will over rev, so maybe smart tabs are my answer. Anyone else?

 

[steelespike]

Re: I need better low end

I think at that age I would check compression.then parhaps a good tune up with careful timing check etc. Even though it has always been slow age can creep up on you.In my opinion if all checks out trim tabs are the best invrestment.it will plane quicker,stay on plane with less power,will help resist no wake speed wander and improve ride.

 

[erlindbl]

Re: I need better low end

Agree with the above. I had a similar boat and engine and the 19P should be the best bet as far as a prop. If you have an aluminum, you could go stainless but I would put my money into the smart tabs.

 

[geezlouise]

Re: I need better low end

I put the 80lb stainless steel smart tabs on my Tahoe Q6 last month. They did everything they are touted for. Faster planing time, less bow rise, more slow speed control, and a much smoother ride in chop...but I lost some top end...not much...down to about 45 from 48. I called the factory and they said to adjust them for less down force. I adjusted them down to the lowest point...still too much down force. The factory sent me the 60lb struts to trade out and I installed them in about 5 minutes. Haven't had the boat out yet but I am confident the 60's will be right. Another guy with the same boat as mine said he had to do the exact same thing and it worked perfect. If you can get past the mental part of drilling a few small holes in your transom, the smart tabs are definately the way to go. It took me about 2 hours to install them originally. I could install a set now in about a 1/2 hour since I understand how they operate. A different prop might give you more hole shot but that would be it. The tabs do so much more.

 

[SteveDavis]

Re: I need better low end

So how about this, what prop would I use to get better low end?

 

[geezlouise]

Re: I need better low end

You are running a 14.5 X 19 currently and get 55mph @ 4600 rpm. I think you can run the 4.3L engine up to 4800 rpm before you go past redline. You don't have a whole lot of room to change things. You might want to check with a prop store and run this by them. They can do things with props like cupping the edge and other tweaks.