Diesel engines in speed boat
10-12-2008, 11:00 PM
#321
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Cat factory bought the boat from GLPP and has been using it to test some of their bigger engines. Updated the boat to a big single.
Merritt island was the last place I saw the boat a few years back. Ringhaver/Ringpower was/is involved with handling the test program for the factory the last time I heard. Great group of folks to work with.
Merritt island was the last place I saw the boat a few years back. Ringhaver/Ringpower was/is involved with handling the test program for the factory the last time I heard. Great group of folks to work with.
10-13-2008, 03:42 AM
#322
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One thing we learned during testing was if we put a large enough vent tube to allow the engines to spool up and then mechanically shut-off the air supply to the vent tube with a device (flapper valve) that could withstand the suction of the propeller during the transition the boat hooked up immediately and the hole -shot was incredible.
10-13-2008, 08:13 AM
#323
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more on "FIVER"
The boat I have is a wellcraft 50 scarab meteor. The twin 725 hp seateks go straight to the fixed surface drives. Hole shot in a 50' go fast is not really a priority in my opinion and thats why i went with the surface drives in the first place. Having said that, I was really expecting the engines to struggle at launch as everyone had said would happen. Getting over the "hump" is not the problem for this set up as the engines and turbos are spooled up to 3100 right away...this surprised me in a good way. Its the big props that dont grab if you floor it.
If i gun it the boat sits back and the bow comes up...in a surface drive boat that is unusual. However, launch at 2700 just when the turbos are spooled and away you go. perfect. A bit of delay compared to the trs stuff but what fun. I am thinking about all that exhaust going to the top of the prop and wondering if at 3100 there is too much air...i like the flapper idea for limiting exhaust if you wanted that immediate hole shot...for this boat i am in the zone so no changes for me. Wish someone had a reasonable priced 600hp diesel and I would build these for a living along with the kit cars.
Gotta say again though..how nice it would be to have two 5.9 cummins marinized and connected directly to a trans and a fixed surface drive like the q-spd in a lighter 40 footer.....no hydraulics, no corrosion, no huge parasitic i/o dragging through the water...and a rooster tail to boot. Good times I think.
One more side story...a few weeks ago we are flying through falmouth woods hole with two families(12 of us) in FIVER...two nice go fasts come out to meet the rooster tail and we all had a great drag race on the way to vineyard haven..kids loved it. The cool thing about these diesels is the all day long 55 mph cruise...i just dont have the full throttle reliability worries that i had with the 454's/trs.
If i gun it the boat sits back and the bow comes up...in a surface drive boat that is unusual. However, launch at 2700 just when the turbos are spooled and away you go. perfect. A bit of delay compared to the trs stuff but what fun. I am thinking about all that exhaust going to the top of the prop and wondering if at 3100 there is too much air...i like the flapper idea for limiting exhaust if you wanted that immediate hole shot...for this boat i am in the zone so no changes for me. Wish someone had a reasonable priced 600hp diesel and I would build these for a living along with the kit cars.
Gotta say again though..how nice it would be to have two 5.9 cummins marinized and connected directly to a trans and a fixed surface drive like the q-spd in a lighter 40 footer.....no hydraulics, no corrosion, no huge parasitic i/o dragging through the water...and a rooster tail to boot. Good times I think.
One more side story...a few weeks ago we are flying through falmouth woods hole with two families(12 of us) in FIVER...two nice go fasts come out to meet the rooster tail and we all had a great drag race on the way to vineyard haven..kids loved it. The cool thing about these diesels is the all day long 55 mph cruise...i just dont have the full throttle reliability worries that i had with the 454's/trs.
10-13-2008, 11:34 AM
#325
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With a bravo you could hook up the through prop exhaust and put a silent choice like flapper on it to close off the through hull exhaust. Then you drill some holes in the side of the prop. Just before you slam the sticks you close the through hull exhaust off. That diverts the exhaust through the prop and the holes in the side of the hub aerates the prop so it slips till you get enough forward motion to out run the bubbles. Then the prop hooks up for some serious whiplash. When you feel the snap you crack open the through hull exhaust.
Later he used bottle compressed air that he connected to the turbine housing ,and the boat accelerated good .
10-13-2008, 03:41 PM
#326
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Its a way to give it a try ,but it didn,t work on a boat overhere with a Steyer /XR drive combo,the engine simply had not enough exhaust pressure to aerate the prop ,it kinda bogged the engine even more ,probably if there is no spool there,s little exhaust pressure .
Later he used bottle compressed air that he connected to the turbine housing ,and the boat accelerated good .
Later he used bottle compressed air that he connected to the turbine housing ,and the boat accelerated good .
10-13-2008, 04:37 PM
#327
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i think the big 6" exhaust in front of the surface prop is about as good as it gets in a big boat...if you run high hp engines in a relatively light boat... like most of us do if you want to move along...then the launch is fine. i think it would be trouble without all that torque from the 10 liter diesels though.
10-13-2008, 04:48 PM
#328
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Wish someone had a reasonable priced 600hp diesel and I would build these for a living along with the kit cars. fact5
www.buckdiesel.com
www.buckdiesel.com
10-13-2008, 05:13 PM
#329
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Fast equals how many MPH?
Ok, we need to get on the same page here. Everyone is talking about speed, acceleration, etc but we have no benchmarks.
So,
how fast do you want a diesel boat to go?
That is how we get to (for arguments sake) what is needed to get there.
In my eyes 65-75 mph is useless. You can get most of todays35' -42' gas powered boats to run that fast with pretty mild engines.
My idea of diesel offshore powerboat is 100-110 mph.
The reason I say this is because I think that is where you start to have un-reliable/short lived gas engines. So, if you have diesels boats running that fast you have an advantage.
So, how fast do you want a diesel boat to go?
What do you want from a diesel powered boat?
Joe Gere
So,
how fast do you want a diesel boat to go?
That is how we get to (for arguments sake) what is needed to get there.
In my eyes 65-75 mph is useless. You can get most of todays35' -42' gas powered boats to run that fast with pretty mild engines.
My idea of diesel offshore powerboat is 100-110 mph.
The reason I say this is because I think that is where you start to have un-reliable/short lived gas engines. So, if you have diesels boats running that fast you have an advantage.
So, how fast do you want a diesel boat to go?
What do you want from a diesel powered boat?
Joe Gere
10-13-2008, 06:52 PM
#330
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i have a 26 ft with 44o yanmar diesel 2 speed trannie and fixed surfacedrive at 4 deg all in weight at 2.35 ton im having a serious problems getting it prop,ed right 4 blade mercury runs 10 mph faster than a 3 blade mercury currently running a 17x 26 4 blade but its 400 rpm too big i was thinking about five blades with less pitch what you guys think
