props rpm s f-36 454 crusaders

[duchess]

Gentlemen here s a question for the other f36 owners. I have had Duchess 8 years. presently has 835 hours . Always kept in top condition I admit to being anal about her and her motors. Early this year i tipped the bottom and had it hauled. I have had the same props for years 20 by 21 3 blade no cup. She usually turned 4 to 4100 with 300 gallons and two people at 2800 she ran 17.5 to 18 on a moderate day with no tabs. Sent out and got a pair of used props Murphys prop shop in virginia, They were 20 by 22 which they cut and pitched to 20 by 21 with a slight cup. Duchess now runs 20kts at 1800 but i can only get 3600 with about 280 gallons and 4 of us guys on board. my old props have been reconned . What do you think the problem / answer might be . also what size and pitch are the other crusader f 36 owners using ? By the way murphys is a good shop with good priceing. Also, went out for strippers this A M but had to return to the dock and change my Racor filter and primery filters on the crusaders due to dirt in the fuel which plugged the filters changed same and she s running properly again. thanks for the answers in advance. also I have modified my lower helm if any of you want pics sent me an e mail and i will send pics

[prowlersfish]

Sounds like you need to take the cup out when you say cut the prop you mean remove pitch I how . murpys is good But I like bay better my self .

[Stripermann2]

You went out for Strippers this morning! I guess it's a Trojan thing...

I'd like to see pictures of the helm set-up. You can email them or post them.

Also a discussion here:

http://www.trojanboats.net/wforum/viewtopic.php?t=2513

Thanks.

[prowlersfish]

I would like to see the helm station also

[ready123]

I have had the same props for years 20 by 21 3 blade no cup. She usually turned 4 to 4100 with 300 gallons and two people at 2800 she ran 17.5 to 18 on a moderate day with no tabs. Sent out and got a pair of used props Murphys prop shop in virginia, They were 20 by 22 which they cut and pitched to 20 by 21 with a slight cup. Duchess now runs 20kts at 1800 but i can only get 3600 with about 280 gallons and 4 of us guys on board.

That suggests to me that they did not in fact reduce the pitch! You are getting more speed for same rpm. You could put your old ones back on now they are fixed and be back to what you want. Take your spares somewhere else to be re-pitched.

[prowlersfish]

Adding cup will act like adding pich

[ready123]

I wwould not expect slight cup to have that much effect.... I stand by my suggestion that the pitch has not been reduced. Have them remeasured.

[prowlersfish]

That depends how much the slight cup is. A slight cup can easy put thesame load as a inch of pitch

But I would still recheak the pitch and if its right remove the cup, in fact I would remove the cup even if the pich needs to be ajusted after all

[duchess]

thanks for the replys be a little patient i went out to the boat and took some new pics i will get them to you by next thursday Tom

[prowlersfish]

I just ran some numbers on a prop calcuator . If you add cup to the prop it comes up 1.2" less pich so when took of a inch of pitch the added cup you just lost what you had gained . So like ready123 said have the make sure they made it 21'' pitch and Like I said then make sure they remove the cup . if you want cup you need to go down to 20" pitch

You did say slight cup , so not sure if it would = 1.2" pitch

Note a repitched prop is not as good as a prop that was made at the need pitch as the blades have slighty different "twist" to them , thats why they will only repitch so far.