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Old 02-27-2012, 08:28 PM   #1
Join Date: Feb 2012
Posts: 2
Hull speed

I am new to*mainship froum, I am in the process of*buying a 37ft Motoryacht in Braintree Ma. I am going to move the mainship to The Philadelphia area on the Delaware river. She has twin Gas powered*{marine power} 454s. Any ideals on how to get the best valve for my gas dollar ?* I am thinking about running at hull speed, any body know what that is* and what rpms i should run at. I am not limited by time, trip is about 375 NM,* any help would be appreicate

************************************************** *************** Thanks* Bill

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Old 02-28-2012, 09:41 AM   #2
Join Date: Aug 2011
Posts: 577
RE: Hull speed

Since you are going to be bringing it down in a river, resist the urge to try running it on one engine with the other shaft locked into position. You may need the maneuverability. If the engines are in a good state of tune (they can idle or run at low RPMs without fouling), I'd say to run both engines at around 1000-1200 RPM and take what speed it gives you. If you are going to keep the gassers MHO says to get FloScans to help you be able to dial in max efficiency. Beware,they can become an addictive game, trying to optimize everything!

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Old 02-28-2012, 05:01 PM   #3
Join Date: Aug 2011
Posts: 577
Hull speed

Yes there are lots of opinions. Here is my take on all the info out there and my personal experience.
1) it has been generally agreed upon that the locked down prop doesn't provide enough drag vs. a free spinning one to take a chance on the damage it can cause to the trans.
2) If you do go this route rig up a quick release incase you need that engine PDQ. A big fat pipe wrench around the flange may work but...I wouldn't chance it
3) I plugged a fuel filter coming into Boca Grand inlet and wound up anchoring right in the middle of the channel on a hard out going tide. I was on the bow with my wife watching to see if the anchor broke loose for an hour or so waiting on TowBoat. I went back into the cabin after a while to get something to drink and heard this odd "moaning". "Oh Shi*!" What now. Pulled up the rear engine hatch and and the sound was the windmilling prop spinning the trans! It didn't sound like my Velvet Drive liked freewheeling for that short period even at about 5kts. So I know I would either lock it down or power it at an idle just to make sure the pump was lubricating the trans. YMMV this is JMHO.

I apologize for the hijack as well and I'll delete this if the OP wishes (just PM me)

-- Edited by twiisted71 on Tuesday 28th of February 2012 06:04:08 PM
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Old 02-29-2012, 08:21 PM   #4
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City: Philadelphia
Country: USA
Vessel Name: Dreamers Holiday
Vessel Model: Mainship 390
Join Date: Jun 2010
Posts: 518
RE: Hull speed

Hull speed on that boat is about 8 kts. I'm not sure what rpm you will need to run to get there, you'll need to check once you start running. i have a 390 and the LWL is roughly the same. Where on the Delaware are you going to keep it? I'm at Riverside Marina in Dredge Harbor
Dreamers Holiday
MS 390
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Old 03-01-2012, 04:08 PM   #5
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City: Joe Wheeler State Park, Al
Country: Cruising/Live-Aboard USA
Vessel Name: Serenity
Vessel Model: Mainship 36 Dual Cabin -1986
Join Date: Jul 2011
Posts: 1,250
RE: Hull speed

Old Stone wrote:
........*My Egg Harbor will burn 40 gals/hr at speed, but down to 10 -12 when mosying along. That's why I don't take that boat out very often.
*Since I haven't gotten a trawler/motoryacht yet I am open to all options in engine size and boat size/weight.

What size is your egg harbor and I would thing mosying along would be about 7kts?

Thanks in advance

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