10M Express what is the best prop?

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Trojan10m
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Re: 10M Express what is the best prop?

Post by Trojan10m »

I have acquired 1.91 transmissions I am not sure what boat they came out of and installed them now twice in the last 4 days. I installed the port trans and match the new transmission with the same rotation. When I put it in forward it goes in reverse and vice versa. So today I swapped the second transmission on the port side and rotated the pump to go with the rotation of the motor and now the boats still does the same thing. If anyone has any ideas I am open. Port motor is standard rotation and starboard motor is reverse rotation.

Once I get the transmissions figured out I will need to know props sizes. Looking back it looks like 4 blades is where I need to go, but you all didn’t put what you had. Are they 18 x 18?

Thank you again.

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RWS
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Re: 10M Express what is the best prop?

Post by RWS »

1983 Express same gears as you

my most efficient props were 4 blade 18 x 19

stock 9x24 trim tabs replaced with 12x24 tabs with 3" drop fins - this is a DIRECT, BOLT-ON REPLACEMENT

remove exhaust diverters

replace stock breathers(spark arrestors) with taller ones - BEACON MARINE

check and set spark advance with an ADVANCE TIMING LIGHT

RWS
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1983 International 10 Meter
Yanmar 315 diesels
Solid Glass Hull
Woodless Stringers
Full Hull Liner
Survived Andrew Cat 5, Direct Eye of both Charley Cat 4, & Irma Cat 2
Trojan International Website: http://trojanboat.com/

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prowlersfish
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Re: 10M Express what is the best prop?

Post by prowlersfish »

Trojan10m wrote:
Thu Sep 02, 2021 9:57 pm
I have acquired 1.91 transmissions I am not sure what boat they came out of and installed them now twice in the last 4 days. I installed the port trans and match the new transmission with the same rotation. When I put it in forward it goes in reverse and vice versa. So today I swapped the second transmission on the port side and rotated the pump to go with the rotation of the motor and now the boats still does the same thing. If anyone has any ideas I am open. Port motor is standard rotation and starboard motor is reverse rotation.

Once I get the transmissions figured out I will need to know props sizes. Looking back it looks like 4 blades is where I need to go, but you all didn’t put what you had. Are they 18 x 18?

Thank you again.
The 1.91 transmissions change the output directions. When Trojan used them, they put the standard rotation (LH rotation) on the starboard side. And put the reverse rotation (RH) engine on the port side. So there are 2 ways to go in this case and keep the 1.91 gears. You can swap the engines or swap the props. I would do the prop swap myself and see how it does. You are not the first to have this happen. And you won't be the only boat with a LH prop on starboard and RH on the port. There may be a slight difference in handling/ lift.
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77/78 TROJAN F36 Conv.
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Trojan10m
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Re: 10M Express what is the best prop?

Post by Trojan10m »

Thank you I will work to get 18 x 19 props. And probably swap props for the resst of the season, until I swap the motors.

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RWS
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Re: 10M Express what is the best prop?

Post by RWS »

point of reference:

on my 1983 10 meter express, one Crusader motor ran clockwise, the other, counterclockwise.

I am not aware of any gears running in reverse

BEST !

RWS
1983 International 10 Meter
Yanmar 315 diesels
Solid Glass Hull
Woodless Stringers
Full Hull Liner
Survived Andrew Cat 5, Direct Eye of both Charley Cat 4, & Irma Cat 2
Trojan International Website: http://trojanboat.com/

WEBSITE & SITELOCK TOTALLY SELF FUNDED

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prowlersfish
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Re: 10M Express what is the best prop?

Post by prowlersfish »

RWS wrote:
Sat Sep 04, 2021 7:52 am
point of reference:

on my 1983 10 meter express, one Crusader motor ran clockwise, the other, counterclockwise.

I am not aware of any gears running in reverse

BEST !

RWS

The 1.91 gears change the output direction due to their gear setup. That's why you would find most boats with them have the reverse rotation engine on the port side. This includes the 10-meter express. They are not running in reverse as that is their normal opp. Unlike your hurt/ZF gears only the forward clutches can handle full power.
Boating is good for the soul
77/78 TROJAN F36 Conv.
6BTA Cummins diesels
Life is to short for a ugly boat :D

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prowlersfish
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Re: 10M Express what is the best prop?

Post by prowlersfish »

Trojan10m wrote:
Sat Sep 04, 2021 6:31 am
Thank you I will work to get 18 x 19 props. And probably swap props for the resst of the season, until I swap the motors.

Did some checking. Trojan had 2 boats a 13 and a 10 meter that they tried the props on the opposite sides. there was handling issues. reverse was a bigs issue said you could not back up referring to the 13 meter assume the 10 had similar issues. I am assuming the prop wash from the other prop. so bear this in mind. This was from John Leeds a Trojan engineer.

Please use know what happens
Boating is good for the soul
77/78 TROJAN F36 Conv.
6BTA Cummins diesels
Life is to short for a ugly boat :D

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BobCT
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Re: 10M Express what is the best prop?

Post by BobCT »

I made this mistake when I repowered, put the props on the wrong sides. I could have left them because the ZF transmissions can run full power in either direction. Ideally, you want the props spinning away from each other towards the outsides of the hull. Very easy to get confused when you're dealing with engines, transmissions and props that can spin in either direction. In my case, I now have engines that both spin the same, transmissions in either direction but I'm still used to the 454 CW and CCW engine rotation setup.

Throw in a reverse threaded packing nut and it's a whole lotta fun keeping everything straight.
1988 10m mid cabin

ecraigsmit
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Re: 10M Express what is the best prop?

Post by ecraigsmit »

my10meter wrote:
Sun Jun 13, 2021 6:44 pm
My 10m Express has 454s and 192..1 trains. Replaced with 4 blade props. 3150 cruise 23.7mph under heavy load. 23.7 is the sweet spot for efficiency. Data collected from 9000 hrs of use
Capt Dana, I have the same stock setup on my new-to-me 10m express and would love to cruse at 23.7mph and are you saying you get there at 3150rpm :D :D ? If so, can you please provide more details on the 4 blade props you are running (dia/pitch/cupping)?

Trojan10m
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Re: 10M Express what is the best prop?

Post by Trojan10m »

I have decided not to swap the props and just going to swap the motors this Saturday. I have also borrowed a set of 4 blade 18 x 19. Let’s hope this switch is the end of this project for a while. I am ready to enjoy the end of the season.

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