Props for 10 meter mid cabin

[koviak]

Has any one repropped or repitched there 10 meter? Looking at making it slightly more effecient at cruise speed (3000rpm). Would 4 blade make a difference other than better low end performance? It's winter in Pasadena Md. and I am bored so I start planning for next season. Oh yeah it has 454 crusaders.

[ready123]

Another advantage of going to 4 blade is that you get more transom lift... helpful to a Trojan's cruising attitude IMO.
I notice my backend sits up more with my 4 blades vs when I use 3 blade. She seems to get on plane earlier... though I have done no testing or measurement comparisons to prove that... just happy to go along with the theory. My fuel consumption and cruising speed have also improved.

I don't care about any slight loss of max: speed. Docking and low speed manouvering is much improved too.

[captainmaniac]

Ready... a little off topic for the thread being about propping a 10 meter, but was curious what 4 blade you were using... I know the 'standard' 3 blade for the F32 is a 16x16 cupped, but what diameter / pitch of 4 blade are you running? I'm always looking for things to improve running angle and fuel economy.

[RWS]

The transmissions, shafts, logs& props are set up differently on the 10 meter mid cabin models vs. the express curisers.

The engines are farther aft, the shaft angle is different requiring smaller props spinning faster with different ratio transmissions than the express cruiser models.

I ran 4 blade 18 x 19 props on the express cruier, however I cannot help you with the mid cabin.

There are a lot of mid cabin guys on this forum who can help.

RWS

[my10meter]

My 10 meter express came with 3 blade props when I purchased her 2 months ago- Are the 4 blades OEM or did you switch to them after the fact? The previous owner of my boat has a set of 4 blade props that kept--18x20's and he is willing to sell them to me. He claimed to get 2 more mph of cruise speed and also said the rear of the boat rode higher.--lift. My 10 mtr has 350hp 454's and with a half tank of fuel -3300 rpms - cruise is 24mph. I really would like a spare set of props- and at the same would like to make an improvement- Do you believe the 4 blades are worth going to?
Thanks
Capt Dana

[gardnersf]

Hmm 3300 RPM and 24 mph sounds a little off. I get about 18 knots (20 or so MPH) at 33-3400.

[ready123]

Ready... a little off topic for the thread being about propping a 10 meter, but was curious what 4 blade you were using... I know the 'standard' 3 blade for the F32 is a 16x16 cupped, but what diameter / pitch of 4 blade are you running? I'm always looking for things to improve running angle and fuel economy.

I believe the 4 blades that came with my F-32 are 17x14... as she is away for the winter I cannot confirm, so need to rely on my memory, which can sometimes be questioned at my age.

Anyone else with an F-32 know for sure the sizing

[my10meter]

The figures I am quoting are from actual GPS runs in mid October- calm conditions- 3300 rpm 24mph on the GPS- My boat is a 10 mtr express- There are 2 other 10 meters at my dock but they are mid cabins--the mid cabin weighs more (because of the extra glass for the raised cap- mid cabin area- and the stringer system is encapsulated wood vs the vacuum bagged solid glass liner that is in the express models) and have a prop angle that is not as efficient-(shorter shaft on a greater angle) The mid cabins are getting 2-3 mph less at the same rpm.

[RWS]

In addition to the different shaft & prop angle, mid cabins also have different ratio transmissions spinning a smaller prop at a higher RPM.

Here's the graph of my non-mid cabin, 1983 express cruiser model with the 4 blade props BEFORE the changeout to diesels.

Note these 454's were a bit on the tired side.


RWS

let's try this...

[ready123]

Here's the graph of my non-mid cabin, 1983 express cruiser model with the 4 blade props BEFORE the changeout to diesels.

It would be really interesting to see the same graph with the diesels, any chance of that

[RWS]

I wish I could do such a graph for the diesels.

That graph was done with a GPS, digital tach/synchronizer and a Flowscan.

I don't have a flowscan on the boat now. I have been told that the sensors (2 per engine) are suseptible to issues with contaminats found in diesel and that they hav a comparatively short life. These sensors are expensive to replace and the whole flowscan outfit for the diesels is very expensive a well.

The Floscan for the gas engines was only about $350 toal cost or so and was well worth it. The boost guages and pyrometers on the diesels show me exactly where my sweet spot cruise is, but they don't give me a burn rate at any given RPM or load rate.

Also, the boat was sporting the larger trim tabs 12" with drop fins vs the factory 9") for those tests, the factory intake breather spark arrestors were replaced with 1" taller units and the diverters had been machined out of th Y pipes in the exhaust.

RWS

[my10meter]

RWS-
Do you still have the floscans and are you looking to sell them?
Next - I was wondering if the taller flame arrestors would make a difference- Glad to here to someone beat me to the punch- did you find a significant difference?

The y pipes-- I am assuming this was create better flow--did you remove the extra material from casting the part?

I have worked in a perfomance shop--every little bit helps-
In a gas hogg- little differences mean lots of $$$ at years end.
I will be putting about 500hrs a year on this boat.

Thanks
Dana

[RWS]

The digital tach/synchronizer has been sold and the flame arrestors went with the engines.

I think the flowscan is still available. It's with 1st mate marine along with the props. See the PM I sent earlier.

RWS