prop recommendation
 

I have an 89 Wellcraft Eclipse 216 bowrider with an Alpha I drive, and a Mercruiser V8 engine (not the 5.0ltr) Not sure if this makes a difference but i will be converting to Rex Marine Captains call exhaust system over the winter. I use the boat for tubing, and water skiing with the family and friends and typically will have 4-8 people aboard. The boat is used in lakes most of the time.

The last prop on it was a three blade aluminum 19pitch cheapo aluminum prop (rounded tips) dubbed by my friends as a "tug boat prop". Turning that prop I was at 4600rmp with just me aboard and light on fuel, and trimmed out as best I could This pushed me along at a wholloping 53mph :lolhit: across a smooth lake.

With that said what diameter and pitch prop would you recommend to gain a little more performance... if any? I am thinking a four blade would grab more water so to speak and possibly improve my holeshot thus popping skiers out of the water a little faster so I am leaning towards that? Maybe I should just stay with what I have? Obviously though I am new to boating and am open to suggestions.... and no, a different boat/engine is not an option.

may want to post this in the prop section for bblades to comment on :)

Vensura 19" or LaserII 19". You could opt for a LaserII 21" as high speed prop and then have a High5 17" for tubing, or just use your current alu prop for tubing. If looking for all around performance, go with the Vensura 4 blade. If only using one prop, don't move up in pitch, since you won't get the same blade flex with the SS props as you did with the alu prop. The Revolution4, Mirage+ and Bravo1 are big props, and will be more diameter and blade area than your boat need, and the SBC will like.

I thought of that but I am not a "paid" member so it was not an option.

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Thank you for the input A. O. Razor. Couple of questions:

1. What is the difference in the Vensura 19" and LaserII 19"?

I am interested in an all around good prop. As much as I 'd
like to be rocket out on the water the wife and kiddies
don't enjoy it much as being only 21 feet it doesn't take a whole lot for things to get bouncy!

2. Is their a aluminum four blade prop on the market that
willgive me similar performance ast the Vensura 19" you
mentioned if I move up in pitch to compensate for blade
flex? and if so what would you suggest?

3. Lastly.. what is SBC?

Sorry to be such a noobie on this whole thing... boats are new to me. I was this way with sowmobiles 10 years ago and now I can pretty much provide advice on anything. hopefully someday I will be able to do that in the boating world too.

No problem, we all have to learn.

The Vensura and LaserII are stainless steel props. The Vensura is a 4 blade and the LaserII is a 3 blade. There is no aluminium prop that will give you the performance of an stainless prop, so forget about that. The reason why I say you should not move up in pitch is, and I'll try to explain it simple.
The alu prop have thicker blades than the SS prop, therefore the water resistance from the SS prop is less, and the SS prop will in theory spin faster. BUT, when you put a load on the slu prop, the blades will flex much more than the SS props will, and therefore bring the rpms up, and act like a lower pitch prop. All in all, the 19" LaserII and the 19" alu prop, will spin more or less the same rpm, but the SS prop will use the energy to propel the boat forward, and not flexing the blades. In many cases, the LaserII will actually be both faster and spin a little bit more rpms than the alu prop, and therefore it is sometimes possible to move up in pitch when going to an SS prop. This will give you a good top speed, but will hurt your accelleration, and that you do not need when pulling stuff and playing on the water. Here is where the 4 blade Vensura comes into play. A 19" 4 blade Vensura, will spin slower than a 19" 3 blade LaserII because of the added load and drag of the extra blade. This is also why 3 blades are commonly faster than 4 blades. The 4 blade will give you much better acceleraiton and cruise efficiency than the 3 blade prop, and the Vensura has in several cases shown to be as fast as the LaserII of the same pitch, at a little lower rpms. But because of the lower rpms of the Vensura 19" vs. the LaserII 19" is also why you can't use a 21" Vensura. All in all, the Vensura is a fast prop with good midrange punch and hole shot, that is what makes it such a great prop imo. I hope this makes some sense to you.

One way to devide it up could be as follows.

21" LaserII. Fastest, but at low rpms and reduced hole shot and pulling power. Therefore a good top end prop, but the proor hole shot, weakish pulling power and low planning speed, not the best all round prop for a family boat.
19" LaserII. Not as fast as the 21" LaserII, but with better hole shot and wot speed at high rpms. A decent allround prop, but it does not have a very low planning speed, as with the 21" LaserII.
19" Vensura. Almost as fast as the LaserII 19" but with much better hole shot, lower planning speed and good midrange efficiency. As said before, it is sometimes as fast or faster than the equivillant pitch LaserII, so a really sweet prop.

I'd suggest you contact your local merc prop shop, and see what they have and maybe will let you try. The best thing is, if you can get to try the props first and see what works best for you. www.bblades.com has a test program you could use. Then you could get a LaserII and a Vensura to try for a 40-50$ deposit each. The deposit will be included in the price of the prop you choose, and you will only pay deposit for the prop you don't buy.

Oh, and SBC is Small Block Chevy.

WOW!!!! Very impressive and helpful. Trying out the props is not really going to be an option... through reading what you wrote the 19" Vensura seems to be the prop of choice. Thanks!

Anyone else have any other options. That u think are.worth me considering?

Well I went shopping today and picked up a Mercury Elite Series Trophy plus 14p SS 4 blade prop.... with my limited knowledge I deducted that it was pretty much the same as what was recommended earlier. I got it off Craigslist.... guy was asking $250.... I left with for $200- S tell me... did I make a mistake based on my initial post describing my boat, engine, and drive? Lets hear it guys.....

From what I know that is more for bass boats and big Jon boats running outboards. Also that's way to little of pitch. You probably need a 19P. 4600rpm is where you should be. Assume you have a 350 260hp.

http://www.mercurymarine.com/propell...e/trophy-plus/

:picard1:oops.. typin on a phone can be tricky... (big fingers/little buttons!!!!) Shoulda read, 19p NOT 14!

oh, also after reading my original post again the pitch I posted there was wrong as well!!! I was spinning a 17 pitch aluminum 3 blade last season, not a 19p:picard1:

Two rules of thumb on props is when changing from a 3 blade to a 4 blade you go down one prop size in pitch which usually means 2 inches of pitch. Second every inch of pitch will usually change your rpm's by 200.
I would think your boat would work best with a 19p 3 blade. Going from a 17p 3 blade to a 19p 4 blade you may see a rpm drop of 4-500 or more. May as well try it at this point. You got nothing to loose. Max rpm range for a 260hp merc is 44-4600.
http://www.mercurymarine.com/propellers/prop-selector/#

I would also think your speedometer is wrong for a 17P prop at 4600rpm.Probably more like mid 40's.
http://www.marksmarineinc.com/prop_calc.aspx

that 53 mph was not dirived from the "dreamometer" but was actually a GPS reading...

and power is from a 305 small block, not a 350. I suppose I will just need to find out how thigs work in 4 months or so when winter is over here in CT....providing it ever begins??? I am wondering if I should just put the snowmobiles away, and start getting the boat ready? :lolhit:

Ok, kinda back to square one.

First of all, hmmm, yes a bit of a mistake. No the Trophy+ will be the wrong prop. Not trying to be a stick in the mud, but it is what it is. Still, bolt it on and see what happens, you have it anyway.
This is where it gets interesting and to some, maybe a bit confusing.

Story time.

The Vensura is actually the original Trophy before there was a Trophy+. Then it became the Offshore and now it's known as the Vensura, still same prop. Blades are a bit different on the +, and the barrel is smaller. This is done for the outboards to vent exhaust over the blades when accelerating. What your speed has been with the alu prop is not that important, your rpms are. Basically the same thing goes, but what you then need is a 17". Again the LaserII or Vensura are the props to look for. Sell the Trophy+ and tell the guy who sold it to you, that they are NOT the same props, at all.

For all around performance on your boat, the 4 blade will work the best.

Oh well... I wonder if he wants it back? He wanted 250 and sold it for $200.... if he takes it back at least he will have the opportinity to collect on the $250. I will even c if he wants to keeps a few bucks for his troubles... he did explain the venting that u did A.O. and con.tnued with the Alpha I is the same basic lower end and would work the same as if it were on an outboard... at least he.was trying to be honest with me...

What would u imagine would happen when the exhaust vented over my prop on my I/o?

Blow out when turning, when pulling and when accelerating. Lack of carrying ablillity, over reving, poor trim response and efficiency. possible cavitation burns. Did I mention blow out.

Hahaha...ok, I am convinced... its gotta go! Anyone wanna buy a prop? Hahaha

You said in your first post it wasn't the 5.0ltr.. 305 is the 5.0ltr. 230hp. If your confident that your GPS is correct then your tach is probably wrong. 53 mph with a 17p prop would actually be about 5100rpm's. A 19p, or 2 more inches of pitch would bring the rpm's down by about 400 which would put you closer to the correct recommended max rpm.

The flash arrester reads 5.7 ltr. Which I know is wrong.... and must be off a 350ci motor.

The valve covers read "228" (whatever that is???)

and the sticker on the side of the head reads "305"...

I guess I thought a 5.0ltr motor was a 350.

I am sorry for the confusion. God I hate being new to something...!!! Thank you to everyone for their patience...
Be sure to tell all your friends that have outboards that I have a nice SS prop for sale for cheap.

Website for small pitch Props.
 

Try posting prop here, may help in selling:

http://www.bassboatcentral.com/props4sale2.htm

I will definitely do that. Thank you!