10M Express what is the best prop?

[Trojan10m]

I have a 1982 10M Express, what is the best prop for the boat. Mark IV 454’s with 16x16 cupped is what I am currently running. The best cruising speed I have seen is about 17 mph at 3300. I called Henry Smith Propeller a couple years ago and the suggested 15x15. I thought 16x16 cupped was close enough and didn’t need to spend the extra money.

I have seen people say 23 mph on adds but it is kind of hard to believe that is truth knowing what I speed I go.

I am just looking for the best cruising speed and mpg. I know RWS did a lot of research years ago. But I thought I would see if there is a new crowd to add some data and suggestions. I have seen 3 and 4 blades on 10M Expresses, is one better, or what are the pros and cons.

Please share what props your have. Thank you all for your time and knowledge.

David

[prowlersfish]

What is your wide open RPM and speed? 3 blade ?

Edit Are you sure you have a express not a mid cabin ? Gear ratio ?

[Trojan10m]

I think my max rpm is 4400. Trying to remember from last year or more like 2019...Maybe 23 mph. Yes I have 3 blade 16 x16 cupped. With half to quarter tank of fuel.

Yes it is an express and gear ratio I would have to check, but whatever a 454 330hp crusader had.

[prowlersfish]

Looking at the paperwork I have Trojan lists "10 Meter Express Mid cabin "model 340 that calls for 16x17 sc props and 1.5 gears. They also list a "10 Meter Express" model 330 that uses 18x22 sc props with 2.0 gears. If you had the 2.0 gears and 16x16 you would be slower and rpm would higher

Do not confuse the mid with the aft cabin (common mistake ) Do you have the ID number ? ( you can pm me if you don't want to post it ) or some photos .


I know a lot of questions I want to get it right.

[Trojan10m]

I will have to check the trans for the ratio this weekend. But I pretty sure it is a 1.15 to 1.25.

There are no cabin under the deck. I have v berth, dinette, and stacked bunch beds.

[prowlersfish]

Not a gear ratio used by Trojan . Just the 1.5 and the 2.0 ( really 1.9? ) . But you never know what has been changed over the years . Check both to be sure .

[RWS]

We need to first confirm the hull design to help you.

The express had engines under the helm seating

the mid cabin placed the engines farther aft, with a different shaft angle requiring smaller props spinning faster than the express

I can share my 454 gas express data with you with both 4 blade and 3 blade props.

There are other very knowledgeable owners on this Forum like Bobct who can share mid cabin data

RWS

[Trojan10m]

My gear ratio is 1.52:1.

The engines are under the helm seat. The layout below is a v-berth, dinette on the starboard side in front of the head, and bunk beds on the port.

[prowlersfish]

Well, you describe an Express for sure . But your gear ratio is what is used in a mid. And of course, gear is the # factor . The stock prop for the mid that uses that gear is 16x17 small cup 3 blade . I will do more checking

[RWS]

Well, you describe an Express for sure . But your gear ratio is what is used in a mid. And of course, gear is the # factor . The stock prop for the mid that uses that gear is 16x17 small cup 3 blade . I will do more checking

+ 1

RWS

[prowlersfish]

If you look at Bobct's were he re-powered he was getting 17 knots at 3000 using 17x14 props . His is a mid cabin But it had the 1.5 gears like you

"2,800 RPM's, 15k, 28 GPH
3,000 RPM's, 17.1k, 34 GPH (this was typically right around my old cruise speed)"
And thats knots not mph .

Do you know what engine is left turn (normal ) and right turn (reverse) (engine not prop
Trying to figure out if anything has been changed

Can you get me the numbers of your ID plate? It will be under helm in the doors to the pannel I will find what Trojan put in it new. Only 2.0 gears are listed for the express , but if there was something odd on a boat it will be on the paperwork. I will get Bob/John to check it when I get your numbers.

ID plate looks like this

[Trojan10m]

The port motor is standard rotation, I have had it down to the short block and that motor is .60 over I found out. I did confirm both transmission plates did have the same ratio and appeared to be the same vintage.

I will get the numbers off the plate. Thank you all for your time and knowledge.

[Trojan10m]

Hull No. 333-2050
LH: 34257
RH: 33409
Inspector: 974

Thank you.

[prowlersfish]

Hull No. 333-2050
LH: 34257
RH: 33409
Inspector: 974

Thank you.

I sent it to Bob and John, But are you sure about the 333 (Hull No. 333-2050 ) ?

[Trojan10m]

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