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despy

Regular Contributor
"I have two different props th

"I have two different props that the previous owner of my boat gave me. The one I have been using is the 48-66450 A4 which I believe is a 14.25 inch , 17p . This prop has very wide blades. I also have a 48-36016 A4 which I presume is similar in performance but different in appearance. It measures about 7 13/16ths from centre of hub to end of blades which leads me to believe it is at least 15 1/2 in diameter but has narrower blades.
I can`t seem to locate any info as to what differences in performance I might see between the 2. When looking in the michigan prop crossover, it gives you the closest match in their numbers and both props cross over to the same michigan number.
I can no longer accurately measure the 66450 I had on my boat because the island that was hidden by high tide sort of removed large portions of that prop.
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Can anyone here tell me if I would actually notice any difference in performance with these 2 props?"
 
"Well now I`m really confused

"Well now I`m really confused !! I went to the neighbours boat and saw he was running a 66450 and it also measures out the same from the centre of hub to the end of the blades as the 36016 prop, a little over 7 3/4 inches.
Maybe I`m thinking wrong but if the 66450 blades are the same length as the 36016 but almost an inch wider, would the wider blade not push more water thus push the boat further with each revolution or does the width not make much difference and it is strictly blade length and pitch that matters?"
 
"Barry;
The best prop depends

"Barry;
The best prop depends on what kind of boating you do. Pitch is the all-critical parameter. It is the theoretical distance the prop will move ahead in water in one revolution, not taking into account slip.

For all around use you want a prop that will give you close to rated max Rpm at Wot. This will give you your best top end speed.

If you do a lot of skiing or wakeboarding you may want to drop down about 2" pitch to get better hole shot and pulling power.
If you only cruise you could use 2" more pitch and save a little gas.

Most sterndrives seem to get along with 14.5" diameter props with a pitch that gives best Wot RPM as above.

A prop with too much diameter and wide blades will have huge blade area and will be a dog out of the hole because the engine will be lugging. You want a prop that "slips" enough to let your engine quickly get up to about 3000 RPm from a dead stop, so that you can get moving and get up on plane quickly.

Why don't you borrow your neighbors prop and try it and your 66450 and see which works best?

Rod"
 
"Rod,
Thanks for your replies

"Rod,
Thanks for your replies,
I had the 66450 on, same prop as the neighbour and know about what the performance was.That`s the prop I destroyed on the submersed island. My boat is at left and is classed as a 24 foot Fibreform .Boat supposedly weighs 4000 lbs dry which means I am probably about 5000 with fuel gear and people. The wider bladed 66450 got me about 3900-4000 rpm and a little shy of 40 mph on my Loran. I was only curious as to using the narrower bladed 36016 thinking it might get me on plane a little quicker. The wot isn`t too bad ,as it was, because the manual says that the 233 mercruiser {351 windsor} should be 3800-4200.
I was just hoping someone on this forum might have had tried these two props and could tell me if there was any difference between them considering the difference in blade width, even though the diameter and pitch are the same."
 
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