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.

[Fr. Frank]

Most boat manufacturers do not provide recommended prop data to dealers, unfortunately. Wellcraft used to do so, as did Searay. Proline does, if you buy a factory rigged boat and motor package. The stock props provided by Proline tend to be on the conservative side, i.e.; better suited for maneuverability and economy.

I know that three of the local dealers here allow you to try different props until you find the one that you like best, all as part of the sale of the motor and or boat.

As for high-carbon stainless steel, remember that it is stainless steel, not <font color="brown">rustless steel.

[Bigshrimpin]

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.

Manufacturers don't have the resources to test every combination of power, b/c there are SOoooo many varaibles.

T-tops will shave 3 or 4 mph off top end
Extra weight can slow a hull down 3 or 4 mph
Having the engines mounted too low can shave off 3 or 4 mph.
Props also have an enormous effect on performance. (kind of like trying to run a 40 yard dash in high heals vs. barefoot vs. sandles vs. army boots.

Also you can't compare an overpropped boat with 19 inch 3 blade vipers to 16 pitch 4 blade props and conclude that 4 blade props are superior to 3 blade props. That's comparing apples to oranges.

I've messed around with a bunch of props and have seen stern lifting props like the Mirage Plus and Rev4 dramatically improve the WOT speed/minimum planing speed/ride of seacrafts compared to some other props (michigan rapture, Stiletto Advantage, Stock merc blackmax props, Stock yamaha props).

Anyways you get the idea that it's very difficult for a boat builder to make a claim about performance when there are too many variables that contribute to a boats speed. It's just not worth the aggravation to have to explain to a disappointed owner why his tricked out boat with a Tee Top, 600lb baitwell, 150 gallon fuel tank (full), with twin (PIG 200hp verados) won't achieve the same speed/economy as a stock well balanced barebones hull with a single lightweight engine (20+ year old two stroke). If I were a recreational boat builder . . . I would guard performance numbers with my life and leave it up to the message boards.

[thedog]

you guys are too easy on the boat and prop manufacturers
first off, stainless steel is stainless steel. T316 ss does not show signs of rust in salt water especially if it is passivated.
there should be no rust on a stainless steel propellor in any water period

And to think a boat manufacturer would not be interested in the performance of different engines and prop configurations on boats they produce is ridiculous.
have the dealers write to the manufacturer with what prop and engine configuration is doing on each boat. simple
this way your customer service dept has this info at hand and can tell you as a consumer what to expect with a certain set of motors and props.
take the guess work out of a product, can not be too hard to do. the current owners of seacraft should be sticking their head in the sand not knowing what their boats can do, expecially on a model that hasn't changed in a least 10yrs
don't seem right to me,

[Bigshrimpin]

Clean up the prop with a $2 bottle of toilet bowl cleaner when it becomes "unbearably rusty".

Also I think I wasn't clear . . . Boat manufactures have a good idea of what their boats will do with what power, but customers are a PIA when their boats don't perform as stated. It's not the manufacturers fault either . . . Riggers and customers setup the hull . . . a few hundred pounds of extra weight in the wrong place can be the difference b/w 3.4mpg and 2.8 mpg cruise. A customer that doesn't know how to trim out the boat properly won't achieve the specs . . . is that the manufacuters job to teach the dumb owner how to drive? Hell No!!

Air Density also has a big effect on power . . . so you need to make sure that the tests are done under the same conditions when comparing power. Wind, Tide, wave height, etc all effect performance numbers. There's just too many variables to control.

http://www.go-fast.com/Prop_Slip_Calculator.htm

Can you see the problem now with posting numbers now? It's much smarter for them to suggest props and power rather than provide exact numbers (which is a lose . . . lose deal for the builder). It's not that I wouldn't want that information as a customer, but I understand and respect their position for not releasing that information to the public.

Unfortunately uneducated folks making decisions from magazine performance numbers would be pissed off when the numbers don't match up.

I wonder how many Seacrafts sold in 2005, 2006, 2007, 2008. I doubt it would be enough to put together a spreadsheet with all the different power combinations, but I don't know that for sure. You'd have to follow up with each owner after the engines are broken in too. Anyway . . . It's just not worth it IMO, b/c the data would be junk.

[eggsuckindog]

I wonder if you find a set of 17 Mirage+'s to try out - theres a bunch out there maybe you borrow set sometime -although those decent numbers and we don't run WOT much