Prop advice

[Dillingpt]

Recently purchased a 2003 Chaparral 200 SSI. Love the boat for my family. Stable and steady.

1) I would like lower planing speed for towing kids and better bite in corners.
2) Current prop. Solas aluminum 3 blade 14.8x19
4) WOT 4900rpm. 47 mph by gps. (~900# load + 30gal gas. Mild chop)
5) Engine. Volvo Penta 5.0gl-c (220hp?).WOT range 4400-4800 rpm. Drive is Volvo SX-M 1.62.
6) boat is 19.5’ long and weighs 3200# (average load will be 800-1400#)

Speed tends to match rpm in mid range. 2600rpm ~26mph, 3000rpm ~30mph....
holds plane at about 2300-2400rpm

From what I have been reading on this and other forums I am considering a 4 blade prop. (with similar pitch and diameter) Will likely stay with aluminum for price. The different brands make this a bit confusing. Any thoughts?
Thanks Erik

 

[alldodge]

Your boat needs so much speed to stay on plane, and changing the prop can change the amount of rpms needed to achieve the speed needed, but not the actual speed. To be able to plane at a lower speed you need trim tabs. A 4-blade might get you more hole shot, but will also take a bit more hp to turn.

Your slip is a bit high for the size boat at 13%, but this could also be because your trimming up just a bit to much at 4900 rpm.

 

[Dillingpt]

So a given hull will plane at about the same speed unless you change it. Like with trim tabs. Different props will get you to that speed quicker but planing speed will remain about the same. Got it. Now that makes more sense. Thanks.
More questions.
I played with the trim while at wot to get max speed. There was a range of trim where it stayed at max speed.
Is slip more a factor of the propeller pitch or diameter or design or something else? Is there a brand with less slip or are they all about the same?
Is “taking more horsepower to turn” a bad thing. Do I have enough horsepower? Will taking more hp give me better or worse performance?

I guess this just highlights my main question. My current prop seems OK. I am new to boating and don’t know if I should waste my time on this but I read that matching a prop to your boat is the first thing you should do to get the performance you want.
All of the specs are in my first post. Should I expect better performance for what I want from a different prop? If I can expect better performance, what prop should I consider?

 

[alldodge]

I played with the trim while at wot to get max speed. There was a range of trim where it stayed at max speed.
Is slip more a factor of the propeller pitch or diameter or design or something else? Is there a brand with less slip or are they all about the same?

As example, a 21 pitch prop will theoretically travel 21 inches thru the water in one revolution. The amount of distance less then 21 inches is the amount of slip. Pitch and diameter of a prop, along with the design and weight of the hull all play a part in the amount of slip. One prop will reduce the slip for one hull but may not for another.

As the boat comes on plane trim is adjusted for best efficiency. When speed is further increase trim will have less effect on max speed. The trim may need a bit more but this is minimal. Once max speed is reached, trimming any further, may show a small increase in speed but the prop slip will increase even more.

Best way to find ,ax speed trim, is once there, note the rpm to speed change. If rpm increase more then speed, then your past the point of max.

Is “taking more horsepower to turn” a bad thing. Do I have enough horsepower? Will taking more hp give me better or worse performance?

The more blades in the water requires more hp to turn due to drag. More blades adds benefits of reducing slip and also increasing lift. So if the motor has plenty of power this may not be a determent with turning the prop, but the increased lift can cause the hull to propose. A bass boat can ride on about 12 inch spot, but a runabout will not reach this same place due to design and weight.

Riding high sounds good but can also get into a dangerous place called chin walking. This is where the boat is going so fast that the hull becomes unstable (search the net)

All of the specs are in my first post. Should I expect better performance for what I want from a different prop? If I can expect better performance, what prop should I consider?

Right now I think your propped close to max speed for you hull. Your best cruise is at 3000 rpm and slip is under 10%. The change I would suggest is to go to the same size prop in stainless steel. The SS prop does not flex as much as aluminum and blades are thinner so less drag. If you try 4 blade, suggest 17 pitch

 

[Dillingpt]

The boat does cruise nicely at 3000-3200.
I am sure SS will be best but I will likely get a 4blade aluminum to compliment my 3 blade which I know works OK. I am a new boater and will likely screw up a few times over the next year and would rather loose a $150 prop than a $500. Plus my son is 13 and will learn to drive as well.
You think 17p even though the current 19p WOT at 100rpm over max range? Interestingly, the turning point prop wizard recommended a 15x15p.
There seems to be quite a difference in the SS and Comp props and especially the customs. But at this aluminum entry level is there any real difference to choose one aftermarket manufacturer over the other besides actually putting each one on the boat?
Any preference between Solas, quicksilver, turning point, Michigan wheel,

 

[alldodge]

Each prop provides a slightly different performance, as to which one will work best is trial and error. Some prefer one over the other, but I think that just happens most times as the one they bought. Find a prop shop, many let you try some

 

[Scott06]

I have used four blades on my boats for the exact same reasons you mention. Had really good luck with a Michigan vortex. Would think a 18" pitch would perform well and accomplish your objectives, plus fairly inexpensive

 

[Dillingpt]

Thanks for your thoughts. With the end of boating season here I will find a prop shop to try a couple in the spring. Local shops do not lend but I get over to the Seattle area fairly regularly and there are some shops there.

 

[alldodge]

Agree most don't lend but many will let you buy one, and keep exchanging until your satisfied

 

[QBhoy]

Try a high 5. They actually do allow slightly slower planing speeds. Loose top wing though with same pitch as comparable.