Need advise on replacing prop

oldrem

Commander
Joined
Nov 7, 2013
Messages
2,002
Finally splashed my 1977 Sylvan Seaman 14ft 8" I call the Sea Monster yesterday. The motor I have is a 1992 Mercury 2 stroke 4 cylinder that came off a pontoon boat. The prop is currently a pontoon prop F12.25x9p. It shot quickly to plane and it popped up to 6200rpm in no time. I backed it down to 5350 quickly and kept that as my max during the 2 hour trials.

I obviously need a more suitable prop and need all the help I can get. Basically I know nothing about what I need other than more pitch. This is a fishing boat, so hole shot is not critical - just need to get from A to B without fear of over revving the motor.

This one appears to have the hub pressed in? Is that necessary? 13 spine shaft.

Thank you,

Eric
 

wahlejim

Master Chief Petty Officer
Joined
Jul 23, 2015
Messages
884
A couple of things to check:

-Mounting height. Pontoon outboard to fishing boat may require some modification

-Tachometer. Verify readings with a shop tach

-Speed. GPS verified with your RPM readings. There are plenty of free apps for your cell phone that will help

I agree you are probably looking at a higher pitch, but more data will help with deciding where to go from here. And the outboard doesn't care if the hub is pressed in or not. A reliable prop shop is invaluable at this point. I have heard great things about props ahoy in Union Grove, not too far from Somers
 

oldrem

Commander
Joined
Nov 7, 2013
Messages
2,002
A couple of things to check:

-Mounting height. Pontoon outboard to fishing boat may require some modification

-Tachometer. Verify readings with a shop tach

-Speed. GPS verified with your RPM readings. There are plenty of free apps for your cell phone that will help

I agree you are probably looking at a higher pitch, but more data will help with deciding where to go from here. And the outboard doesn't care if the hub is pressed in or not. A reliable prop shop is invaluable at this point. I have heard great things about props ahoy in Union Grove, not too far from Somers

Mounting height is spot on - Tach used has been verified - used new Garmin Ecomap Chirp 93sv (gps) for speed and my buddy that came along verified with his phone app

Had a bad experience with PA in Union Grove and won't have any dealings with them.
 
Last edited:

WesNewell

Chief Petty Officer
Joined
Jan 3, 2018
Messages
497
boat 360# with 40hp, I'd say a 14P prop would be perfect. should see a little over 30 mph.
 

oldrem

Commander
Joined
Nov 7, 2013
Messages
2,002
14p prop dropped max rpms to 5k and increased speed to 29.9mph. Don't need any more speed and hole shot is good.
 

oldrem

Commander
Joined
Nov 7, 2013
Messages
2,002
Guess I had a few things to be thankful for yesterday. #1 that no one was badly injured
and #2 there wasn’t more damage.

We had high winds Wednesday gusting to 45-50MPH. As I walked out to put up the flag
yesterday morning, something didn’t look right. I then realized a 75ft pine tree had come
down during the storm. After examining it I felt sick and stormed into the house half
crying and cursing up a storm. Pat couldn’t believe my dumb luck when she came out to
see it.

I had promised Pat I would get most of the outdoor Christmas lights and outdoor decor up
since the entire weekend is supposed to be rain and snow, so got started on that first.
one of my neighbors stopped by and offered his help if I needed it to take care of the tree.
My closer son-in-law phoned for another reason and also offered to come if I needed
help. Stubborn old fart declined both offers.

As soon as I finished the decorations, I grabbed a chain saw and ladder to start on the tree
demo. When I cut the first 10ft section off the tree, I hadn’t accounted for all the vines
that were entangled in the tree and the section swung down like a huge pendulum
knocking over the ladder and sending me tumbling to the ground 20 feet away.

My neighbor Greg saw in happen and came running over to make sure I was ok. After I
dusted myself off he instructed me we were going to do this together lol. He grabbed
another saw and a couple machetes. We went to work bucking some of what was left and
clearing the vines before doing any more cutting.

Greg insisted on climbing the ladder to make the next big cut. Well, that kicked out
knocking the ladder out from under him as he went tumbling to the ground. It was my
turn to make sure HE was ok.

After that we finished the bucking. I convinced him one more cut close to the boat and
another on the other side of the boat and we should be good. As soon as that first cut was
made, the root ball took over and lifted the remaining 25ft back to a standing position.

I removed the forward section of the Winter cover to check for damage. There are
indentations on the gunwale caps and trim on both sides. For now that is the only damage
we were able to find. I crawled underneath and the hull looks unscathed. I had the
jackstand on some 1/4” press board which both the jackstand and jack punched right
through probably saving far more damage. Finished cleaning up about 4 just before
guests were to arrive for dinner.

Tree1a.jpgTree2.jpgTree3.jpgTree5.jpgBoat1.jpgBoat2.jpg
 
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