what's a new prop do?

[iwakeboard]

Hi, i have a 1995 bayliner 1800 LS with a force 120 engine and the prop has gotten a little dinged up over the years. I was wondering if it was even worth buying a new prop, and if so what the best type of prop would be, i know nothing about this. I've heard about holeshot and wot and i do not know what any of this means.. so please help me out here.

im only in the market for a prop probably under 300$ if thats even possible.



Thank's.

 

[SoulWinner]

Re: what's a new prop do?

Are you happy with the performance of the prop you have now? You might consider going to a web site to use the Prop Wizard and see what props are available for your application. I wish iBoats had that Wizard. See, your boat will perform differently depending what prop you have. All this takes into consideration the horse power of your engine, RMP at WOT, and the size and wieght of your boat. A prop the gets you on plane quickly is different from a prop that will maximized your top speed which is different from a prop that is designed for towing skiers and tubes and stuff.

 

[iwakeboard]

Re: what's a new prop do?

thank's soul,

I'm just interested in a prop thats generally for everything, we do tubing, kneeboarding, and wakeboarding, and this one seems to do fine, but its pretty dinged up so i had a thought that maybe a new one would get me that little better acceleration, or top speed, or something like that.

I guess i'm statisfied with the current prop, but when i bought it six years ago it topped out at around 38-39mph, so we've lost about 5-6 since then, is that usual in an older boat or would a prop get me back some of that? So its mostly the top speed im interested in, but it sounds like if i want to get that back i'll be losing the acceleration and needed torque to pull up a wakeboarder.

 

[rogerwa]

Re: what's a new prop do?

If you've got rough edges and chunks taken out, there is reason to beleive that you gain some measure of that performance back.. However, while you are looking at it, it may not be a bad time to make sure you can't get more out of your prop by changing sizes.

With your normal load in your boat you need to be able to achieve the the proper WOT RPMs on your tach, which for this motor should be in the 5K -5.5K RPM. If you can achieve greater than 5500 RPM, then you can increase the pitch value of your prop. This will give you greater top end speed. However, it will also affect low end, out of the hole performance. Its a balance.

If you cannot achieve 5000RPM, then you need to look at reducing the pitch of your prop. Engines do not like being lugged and that I what you are doing. This will lead to shortened engine life.

there are a bunch of other things like cupping and rake and stuff like that but looking at the above factors are the best start.

If your prop sticks you right in the middle of that 5000 - 5500 RPM range, then just replace what you have or file down the rough edges..

 

[rndn]

Re: what's a new prop do?

Consider your prop the tires of your boat. Good performance tires handle better than cheap ones, same for a boat. I switched from the standard 3 blade aluminum toa 4 blade SS and noticed a huge difference. The boat was able to turn sharper at high speeds, ran smoother in rough water, gave better hole shots, higher top end, and better fuel economy. All of this came with a cost of almost $400.00 but it made it a completely different(better) boat all around. For me it was money well spent.

 

[Silvertip]

Re: what's a new prop do?

Increasing pitch does not automatically mean an increase in speed. If the engine is already operating at it's maximum recommended wide open throttle rpm, increasing pitch may actually slow you down because you now placed additional load on the engine. In the first part of your post you said you do lots of water toy stuff and were happy with the prop. Then later you said you were more interested in top speed. your boat has no transmission like your car so the prop does that job. Selecting a prop is a compromise between power and speed. You do water toys -- that takes power. Power = lower pitch. Speed = higher pitch. My suggestion is that you should stick with what you have -- but have it rebuilt or buy a new replacement with the same diameter and pitch. The numbers should be on the hub of the prop. If you want the best of both worlds, buy two props. One for towing and one for speed.

 

[kenmyfam]

Re: what's a new prop do?

I am 100% with Silvertip on this issue.