4 blade prop test results 23ft cc

[thedog]

I thought I would pass on this info. difficult to find specifics of props and motors. the boat is a 23 center console, 150 gal gas, tee top
twin 150 hp etecs counter rotating
props set up by dealer were 14-3/4" x 19 3 blade stainless vipers
these props would not make rpm only topped out at 4950 rpm
although the speed was good, running 28knts at 3500rpm, 38knts 4950 rpm
boat would not plane at slow speeds yet fuel and hole shot was very good
the boat always had to be trimmed with the trim tabs to keep things correct

I replaced these props with 15-1/4" x 16 4 blade stainless props,
ran them last night after a week of tinkering to get them installed right.
I think the performance is much better. I ran the engines out to 5500 rpm
flat out. the hole shot was the same, very good. this is using no trim tabs
just the motors tilt to vary ride and performance
boat ran better with a little motor trim up to raise bow slightly
idle 500rpm 2.5 knts
1000 rpm 5 knts
1300 rpm 6.5 knts
2500 rpm 19knts
3500 rpm gave me a 27knt 32 mph cruise,
4150 rpm turned 30 knts 36 mph
5500 rpm turned 38 knts 45 mph
engines should be working alot easier, and hopefully more economical at cruise speed. although these engines are great on fuel to begin with
total fuel use this season averages 2.75 gallons per hour total (both engines)
1.375 gallons each
and have used one gallon each motor of xd100 oil
that is running, trolling, idling ,this was with the old props

the negatives
manufacturer calls the props stainless steel. yet they use a high carbon stainless steel for strength, so the props do rust. along with the thrust bearing supplied,
props did not come made for this engine even though they were advertised as so. requires shimming and special spacers to make them work right.
don't understand why if carbon is required for strength the manufacturer should make the props out of carbon steel and do it for a third of the cost.

hope this helps someone down the line.
I was dissapointed that sea craft does not keep records of what power, on each boat , with different props yields what results.
they leave it up to the dealers and most of them are clueless. and don't keep exact records of how to prop the boats that they sell, each boat is looked at like the first one ever done.