OFFICIAL 390/40 Motor Yacht Thread

Lowely said:
Last question to bug ya'll with for a bit, I promise!

Anyone in the Northern Va / DC / MD area replaced their isinglass? I'm looking to replace all of it to include the canvas. Going to put in the mesh "U" if possible as well. I just got a quote from Renegade (local Prince William Marina repair shop) and it was $5k. Seems high. Anyone else done this?
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My boat is in MD (I live a short ways away from PWM) and just had a new set of canvas made last year. Look back on this thread at posts #261 and #264 where I posted the results. I used a one-man shop close by the boat I had heard about by word-of-mouth. I would say the price you were quoted is on the slightly low side based on my shopping which included Renegade. I have used Renegade before and they did good work but there is a cost involved when the fabricator has to travel. So, based on my experience I would probably jump on the Renegade bid all else being equal.
BTW, I had mesh inserts but decided to abandon them for the new set. I found the mesh to be incredibly hard to keep clean.
 
Here is a shot of my smart craft screen.
I am running up river in a strong current
On plane.
1CCF2CE3-9AE1-48C6-9726-D076F0111243.jpeg
 
Lowely said:
What is your burn rate in GPH?
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No excuse but the river was full of debri
and I did well to capture that. Rest assured it’s up there. Came back down stream at 21mph on plane but couldn’t take time to look due to it being a Solom
course.
 
RBB said:
No excuse but the river was full of debri
and I did well to capture that. Rest assured it’s up there. Came back down stream at 21mph on plane but couldn’t take time to look due to it being a Solom
course.
Click to expand...

"the river was full of debris" -excuse; that works for me. If the weather holds this weekend we are headed south again. I will try and take a few pics of our boat performance on the trip.
 
Has anyone replaced their exhaust elbows and risers with dry exhaust elbows and if so do you have your old ones and who did you use to do the work?
 
390 Performance 15JUN2020.jpg


15 June, 2020. Potomac River, headed upstream on rising tide. Wind is on the starboard quarter, 4-6 kts. Two people, ~1/2 tank of water, ~1/3 tank of fuel. At 3536/3512 rpm I show 15.6 mph.


Notes: Engine hours are not the same. The port engine has a new ECU and the hours about reflect our actual time on the boat. The starboard ECU shows life-of-boat hours.
 
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Angle390 said:
"the river was full of debris" -excuse; that works for me. If the weather holds this weekend we are headed south again. I will try and take a few pics of our boat performance on the trip.
Click to expand...
Here you go. Up stream is higher rpm and fuel burn.
 
After today I am thinking my sweet spot is 3420 to 3550 rpm with my 8.1s .
Any thoughts from anyone.
 
Lowely said:
20 gallons of water, 2 people, 2/3 tank of gas. 10.6 gph burn, 9.8 its, 2100 rpm
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9.8kts = 11.2 mph SOG. If your gph is cumulative (5.3 gph per engine) then that is really good. You would be getting better than 1 mpg. I think less water in the tank really helps a lot. The fuel is midships so the mass is centered in the boat. But the water is all in the stern, and at 8.34 pounds per gallon, it adds up fast.

We have started traveling with 1/2 tank of water or less. I may start decreasing that down to 1/4 tank of water.
 
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At what rpm do you guys cruise at ?
I talking about on plane.
 
On plane we cruise at 3400-3700 rpm much like Lowely. I have been adjusting the trim on my recent trips. I usually keep it at full trim but when the tide or wind is at the stern I can decrease the trim and get a bit better performance.

I am starting to think that the 390MY is really sensitive to weight, wind and current. I have seen the rpm increase and drop by 200 when we round a bend in the Potomac. A bend in a river usually has in change in current velocity depending on where you are in the bend. It is really strange to see the RPM jump and gain 2 mph for about 5 minutes and then see it go back to where it was. This has happened to me regularly at the same location so I know it is not a mechanical issue.
 
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Does anyone know where the fuse for the co2 detector in master stateroom?
 
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