Volvo Penta 5.0 GXI/larson 230 LXI prop help

My new to me 2004 Larson 230 LXI is equipped with a Volvo Penta 5.0GXI. The current prop is a 3 blade aluminum, 14.25X21.

WOT is marked on the engine info tag as 4600-5000. Not sure what this means, that seems like quite a range to me. I attempted to reach WOT yesterday and was only able to achieve about 4250. At 4250 I was traveling 36 MPH according to the factory speedometer. I forgot to take my GPS in order to get a better speed.

I think I need to re-prop this boat in order to overcome a couple small issues. First, when turning tightly, the boat will 'skip' sideways across the water a bit. When this happens the boat loses speed and 'traction', and ventilates/cavitates (Yeah I've read the definitions and am still confused, I'll keep studying that). On a similar boat with similar issues, I re-propped with a 4 blade stainless prop and it solved the problems. So... the question now is what size/pitch??

Most of our boating is on low elevation lakes, 1000' or so. We do a lot of tubing, some skiing, and kneeboarding. The boat handles well generally speaking. It planes quickly, with little bowrise. Top speed is not a huge issue, although It is nice to be able to outrun a T-storm if necessary, LOL!!!

Suggestions??? Questions??? Thoughts???

Re: Volvo Penta 5.0 GXI/larson 230 LXI prop help

Really, no suggestions??

Re: Volvo Penta 5.0 GXI/larson 230 LXI prop help

WOT tag is just a range that the motor operates best in... not exact, thats why the range. But shoot for the top of that range. Don't be scared, that's what rev limiters are for I would think that the 305 could swing that 21p and get you going over 40. But it looks like you need to drop down in pitch. I would think a 17-18p 4 blade ss would get the rpm's where they need to be. BUT, hows the condition of the engine? Has it had a tune up, filters, etc? I would hate to spring for a prop when you have other problems. Maybe you don't and the seller just slapped a prop on the boat to sell it. Solas makes 4 blade props in aluminum and stainless. You could try in aluminum until you find the right one... then later on get the ss one. Keep the aluminum around as your backup. Hope this helps.

Re: Volvo Penta 5.0 GXI/larson 230 LXI prop help

You could go with a 19 pitch or probably even a 17pitch prop. You are revving too low and are lugging the engine a bit. I'd try the 17, it should bring up your revs to the required range. You can also go to your local prop shop and see what they recommend, they may even let you borrow a couple of props to try on the condition that you buy one from them.

Re: Volvo Penta 5.0 GXI/larson 230 LXI prop help

Thanks guys!!! As far as the condition of the engine, it is tip top. First the boat was hardly ever run, it had 50 hours on it when I bought it, and secondly, the first thing I did was take it in and have all fluids changed, and a "tune up" done. Point understood though, eliminate the possibly contributing factors.

Your input is helping confirm what I have learned in my reading and studying online. Generally, it sounds like I should drop 1" of pitch when going from3 blade to 4. This would give me comparable performance. Then, if I drop another 2" that would give me approximately 600 RPM's moreon the top end?? So, that puts me going from my current aluminum 21, to a SS 18?

Rev limiter??? Tell me about this?? I am pretty conservative with my equipment. In fact, it was pretty hard for me to allow myself to take this boat to wide open. Is it safe to run this thing to 5K momentarily?? How reliable is a rev limiter?? I've never blown one up, and don't want to do so now, lol!!!

Re: Volvo Penta 5.0 GXI/larson 230 LXI prop help

Sounds good... 18p in a 4 blade Stainless. Going WOT... yes it's safe. You are still within the manufacturers recommended range. Rev limiter... limits the revolutions of the engine... as to not over-speed your engine. Usually done by way of ignition being cut out. I don't think you would ever hit the limiter, unless you trimmed so far as to blow out the prop. But anyways, I think that you will find that even tho the pitch of the prop you are buying is less... and in theory, should be slower, you will probably pick up some mph since you won't be lugging the engine.

Here's some 18p props...

http://boatpropellers.iboats.com/Vo....00&chart=100&engine_id=541&*******=217767123

Re: Volvo Penta 5.0 GXI/larson 230 LXI prop help

Running a prop that won't allow the engine to reach max RPM range is inherently bad for the engine every time you use the boat. So, running at WOT for a moment or two is necessary to get propped right.

When a prop is too big and limits the engine from reaching max RPM range, it is 'lugging'; i.e., it is under --potentially-- a greater load and stress than is ideal. It's hard on the internals. It will speed up wear.

Prop it right, and if you have to enjoy some WOT blasts to figure that prop setting out, then you are obliged to do it!

Re: Volvo Penta 5.0 GXI/larson 230 LXI prop help

90, and philster, thanks for the input. I talked to my boat mechanic today, and he gave me similar information on the rev limiter. I worked out a deal with him to buy a 4 blade aluminum 17 pitch prop to try, he didn't have an 18 on hand. I'll give it a run on saturday and see how it goes. Then, he'll give me full credit on the price toward a stainless when/if I decide the pitch is what I want.

Thanks for helping me narrow it down!! And for helping me realize I can/probably should be running the boat a little harder to avoid lugging it.

Re: Volvo Penta 5.0 GXI/larson 230 LXI prop help

So I ran the 4 blade 17 today, and it was great. I was able to achieve 4850-4900 Rpm's and that put me at 43 MPH on the GPS. Boat seemed to plane even faster, even though it was good before, it seemed a slight bit faster. I think it also planes at a lower speed. So I think I am going to go ahead and order a 17 pitch 4 blade.

Seems like this is about perfect. I was leaning toward an 18, but based on todays test, I think that would be a mistake. Anyone disagree??

Re: Volvo Penta 5.0 GXI/larson 230 LXI prop help

17 sounds just right, you want to be at the upper rpm range... you may drop a few rpm once you have stainless due to the better bite. I am glad it worked out so well. Sometimes these things take more than one shot to get right. Happy boating!