Gear Jammer
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- PeterPalmieri
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Gear Jammer
What do you guys know about this boat?
Seems to have very nicely laid out cabin and prop pockets. Haven't heard about it from this site.
http://uk.yachtworld.com/core/listing/b ... ess=Public
Seems to have very nicely laid out cabin and prop pockets. Haven't heard about it from this site.
http://uk.yachtworld.com/core/listing/b ... ess=Public
1969 31 Bertram FBC "East Wind" hull #315939
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Charlie,
You should be running a 2:1 gear on those 4 bangers. Somebody short sheeted that install.
Those engines are the 315 in that boat 6LP, no need for a prop pocket running a 2:1 gear box.
I've done two 31's with pockets. One was the QSC Cummins 330 1.5:1 gear. While I didn't tweak the prop as much as Bob has, I saw no performance gains over the Yanmar 315's 2:1 gears for the cost of doing pockets.
I've posted pics of this one on the board before.
The second involved a pair of 370hp Yanmars and half way thru the project creative(safety for me) differences caused me to tell the owner to take the boat and go **** himself.
Luckily the job was not contracted and just time and materials.
Never saw it run, but I suspect someone got hurt or there was property damage at some time with it if it ever ran.
Based on my calculations of what gear/prop combo the owner wanted for top end speed, the boat was going to see a 6 to 10 knot idle speed.
You should be running a 2:1 gear on those 4 bangers. Somebody short sheeted that install.
Those engines are the 315 in that boat 6LP, no need for a prop pocket running a 2:1 gear box.
I've done two 31's with pockets. One was the QSC Cummins 330 1.5:1 gear. While I didn't tweak the prop as much as Bob has, I saw no performance gains over the Yanmar 315's 2:1 gears for the cost of doing pockets.
I've posted pics of this one on the board before.
The second involved a pair of 370hp Yanmars and half way thru the project creative(safety for me) differences caused me to tell the owner to take the boat and go **** himself.
Luckily the job was not contracted and just time and materials.
Never saw it run, but I suspect someone got hurt or there was property damage at some time with it if it ever ran.
Based on my calculations of what gear/prop combo the owner wanted for top end speed, the boat was going to see a 6 to 10 knot idle speed.
bruce when you put those prop pockets in you will have to go way way beyond tweaking to get any additional speed to warrant the price of glass work . the post on shooter with 440hp yanmars and this gear jammer with 315hp clearly illustrates what i am about to post; you want pockets no problem you have to reach in your back pocket and come up with $8000.00 in cash and you will get 110% overproped, 21dia., 5 blade, 5 degree rake,special cup beyond #5 , and pitched to produce correct engine rpm plus 50rpm under full load at wot. 5 blade is the absolute minimum .perfection would be 6 blade.as the boat goes forward churned up water is being funneled into the pocket .this white water is filled with air bubbles and then you are "just spinning your wheels".all that work to reduce prop. shaft angle you negated by not following up on desigh . rather silly my boat goes 2 knot faster at wot. and 4 knots faster with 1/3 better fuel enconomy in a much heavier boat with very usefull full lenth,full depth hatches on both sides of cockpit by way of no prop. pocket which really do away with all that valuble room.
capt.bob lico
bero13010473
bero13010473
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- ZeroCavity
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not only shallow but worst yet instead of making upside down u they cut the most important area between the chine and strakes this is where the boat lays on in a hard turn (like avoiding a log in front of boat) . that boat has to go to captain patrick and put a o to 6" tapered keel starting from 6' back from bow all the way to transom or keep it in bay!!!!
capt.bob lico
bero13010473
bero13010473
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