Four Winns prop questions

[TRValeri]

A few months ago I purchased a 2004 Four Winns Horizon 190 with only 80 hours and a Volvo-Pento 5.0 GXi with an SX outdrive configured with a stock 14.25" x 21 pitch aluminum prop. Immediately after purchasing the boat I took it to my local Four Winns dealer for a complete tune-up and inspection and was cleared to go. I took the boat out on the lake today with about a half tank of gas, four adults and loaded up for fun. The lake's surface elevation is 550 feet and the waters were calm. The boat seems surprisingly sluggish out of the hole and with WOT was only pulling 4200 RPM at 45 MPH (as measured by the boat's spedometer). Generally I want to use the boat for family fun and will likely be heavily loaded with 6 or so people most times. I intend to pull the kids around on the lake on an inflatable and pull an occasional wakeboarder. I really don't care that much about top speed compared to better hole shot and more appropriate RPMs at WOT. Finally, I will be running the boat at two lakes with very different elevations (one at 550 feet and the other at 5500 feet), so I likely need two props... so I'm probably looking at aluminim instead of SS just to save some money. With all that said, I'm looking for some general prop advice, etc. Also-

1. Will a 4 blade prop meet my needs better than a 3 blade prop at either lake? I figure the 4 blade will help with hole shot and getting on plane sooner.
2. Given the low RPMs with my somewhat unscientific test today, and provided I go to a 4 blade prop, what pitch do you recomend? I'm thinking something like 18 pitch at 550 feet and about 16 pitch at 5500 feet.
3. Should I stick the the Volvo-Penta brand prop or look at something aftermarket?

Any and all comments will be welcomed and appreciated. Thanks.

 

[TRValeri]

Re: Four Winns prop questions

Hmmm, I woke up this morning eagerly waiting for a response from one of you in the iboat community, but nothing yet

I am new to boating and truly would appreciate your thoughts on my issue.

Many thanks in advance for taking the time to repond. Sorry for the shameless thread bump.

 

[Maclin]

Re: Four Winns prop questions

Good Morning...yawn, where's that coffee....

I did not see this post last nite or I may have commented then. As it is, I may not be much help other than to suggest making sure the engine is indeed in a good state of tune, good gas, etc. Also, I am assuming the Four Winns Horizon 190 is a nineteen footer and normal weight for that size boat.

My first reaction is this, that a 21p prop with that setup should be very responsive out of the hole even loaded up, and should get 300-400 more RPM at the 550 elevation.

I checked the numbers with a prop calculator and your numbers "add up" but I did have to assume the gear ratio is 1.6 and 12% slip with the prop. Nothing unusual there and within the parameters I would expect with your setup, just low rpm for the top speed, and should not be sluggish out of the hole. Again, my opinion. I have included a link to a simple prop calculator at the end of this post.

At 550 elevation the thing should perform very well with the 21p, at 5500 who knows, certainly a 19p would be better up there, but above 5000 things get wierd even with a fuel injected engine so I will defer to boaters with more experience in the higher elevations with that size boat and fuel injected engine regarding prop suggestions.

Verify speed with GPS if possible, also verify the tach readings. In any case, with a 21p in that size boat with a 5.0 it should not be sluggish out of the hole even loaded up, that is just my opinion.

It may also be worth weighing it to be sure it is not carrying around water somewhere. You might also comment on how clean the hull is or isn't under the water line.


http://www.marksmarineinc.com/prop_calc.aspx

 

[TRValeri]

Re: Four Winns prop questions

Thanks for the response Maclin. I don't think I'm carrying any extra water around, but the boat does seems to be very sturdy (i.e. heavy) compared to other 19' boats I've seen. It is absolutley immaculate mechanically and cosmetically, so I don't think there is any extra drag.

I took my boat to the local Four Winns dealer today to have him look it over. He felt I needed to go down in pitch on my prop to deal with the low WOT RPM issue. He had an OEM Volvo 3-blade aluminum prop in stock at 17 pitch, which he felt this would be acceptable since I will be moving my boat up to the 5500' level at Shaver Lake, California in 3 weeks. Does this make sense, or is it going to be too low pitch?

 

[Philster]

Re: Four Winns prop questions

TRValeri:

I think fatigue might be setting in on this subject (another boat turning 4200 RPM, so we want to drop prop pitch to compensate). You have a boat that was checked mechanically and can only turn 4200 RPM under a modest load. Is that prop too big? I think it might be okay if the engine was okay. Forget the high elevation stuff now. Work on the baseline, okay?

Is a 21P prop too big for a 19' boat and a 5.0 V8? No, it shouldn't be. I think it should turn 4500-4600 @ about 48-50 MPH. Now, if you just dive into a 19" prop, you will get the RPM at WOT in an acceptable range. But... is that what we are to do with a 5.0 V8 in a 19' boat? We should turn it into a 40 MPH boat @4500-4600 RPM? Doesn't that seem kind of low for what should be a well-powered boat?

You can continue this exercise, but you have to eliminate two major variables:

>Is the boat heavier than stock (waterlogged)?
>is the engine not running properly?