Sea Ray 390 Sedan/SF and EC trim

F

fighterpilot

Member
Nov 30, 2009
50
panhandle Florida
Boat Info
2550 WA Hydrasport
Stamas 32 Sportfisherman
Californian 34 LRC
Engines
200 Johnsons
454 Crusaders
3208NA 210hp
Look at a 1985 SR 390 Sedan/SF Monday. Owner noted small trim tabs Ok for keeping boat level side to side, but really need larger ones to get the nose down, particularly when aft fuel tanks filled. He indicated he usually jut kept enough fuel in the aft tank to run the generator and used the fwd. two tanks for main engines. I know there aren't many sedan owners out there but does the EC experience the same problems? I believe the hull was the same in both boats. Thanks
 
fighterpilot said:
Look at a 1985 SR 390 Sedan/SF Monday. Owner noted small trim tabs Ok for keeping boat level side to side, but really need larger ones to get the nose down, particularly when aft fuel tanks filled. He indicated he usually jut kept enough fuel in the aft tank to run the generator and used the fwd. two tanks for main engines. I know there aren't many sedan owners out there but does the EC experience the same problems? I believe the hull was the same in both boats. Thanks
Click to expand...

mmmmh ...we do not have an aft tank in our 390 EC :huh:

I can say that the standard tabs are adeguate for me...but I made big modifications on my boat: bigger 4 blade props, bigger diameter shafts and a custom made fixed tab in the center of the transom so that standard tabs are almost not necessary to get on plane (if there's somebody interested in my mods I will take some pics)
 
fighterpilot said:
Look at a 1985 SR 390 Sedan/SF Monday. Owner noted small trim tabs Ok for keeping boat level side to side, but really need larger ones to get the nose down, particularly when aft fuel tanks filled. He indicated he usually jut kept enough fuel in the aft tank to run the generator and used the fwd. two tanks for main engines. I know there aren't many sedan owners out there but does the EC experience the same problems? I believe the hull was the same in both boats. Thanks
Click to expand...

I ran full tabs most of the time...regardless. I think these boats need larger tabs. it's not brain surgery to change them. Consult Bennett as to what they recommend.

Did you consider the one I found down here?
 
Regarding the fuel tanks, as I understand it, the boat has 4 tanks and the two rearmost tanks the owner didn't use, except for the gen. since the boat wanted to bog down with them filled. I agree it does appear that more tab would be benificial. One of my previous boats, only 29 ft. had tabs as big as ones one this boat. It appears there main function was to keep it trimmed level from side to side. In fact the owner of the boat I looked at said it needed much bigger tabs. He had thought about adding them or even adding some structure extending from the stern to help it get the bow down. He did that with a mainship and had the fastest mainship in town, so he said. I guess i could believe that. Anyway, I passed on that particular sea ray but am still looking. Thanks
 
Ray;
Can't speak for the gas power (Sprink just did), but I'm sure the extra heft of the diesels doesn't help. I run full tabs all the time, regardless of load.

No knowledge of the fuel tank layout on the SF either, but 4 fuel tanks sure seems odd. That would require a maze of fuel supply and return valves for the manifold. Far as I know, the hulls are the same. Assuming that's the case, you can see the tabs on mine in this pic. They're as wide as can be fitted, extending from the edge of the hull to the prop pocket. Regardless, if you decide you like the boat enough to sea trial I'd suggest you insist she be fully fueled. It's the only way to know what you're dealing with, including whether the engines turn up to 2800 min. fully loaded at sea trial. I find it hard to believe SR would design a boat that required some of the fuel tanks to be empty to ride properly. I can't help but wonder if the original tank configuration has been changed (the EC's have twin 150 gal saddle tanks).

Good luck.

2007_1112Josea070003.jpg
 
The fuel system on the boat I looked at is 4 tanks. Attached is the fuel valve configuration. Port valve, front and aft tank, and a starboard valve front and aft tank. Also a valve for the Generator. I believe it is factory since i found a brochure for that boat in the archives and it mentioned four tanks. The owner was pretty straight forward with me so I can believe him when he indicated trim tabs were inadequate, particularly with fuel in aft tanks. As far as a boat builder turning out a boat that wasn't perfect it happens. Owner also noted when aft fuel present the side thru hulls were really close to the water. He put shut off valves on them. Tabs are small on this boat. Just on outer portion of the hull on each side.
I will still keep the boat on my list but it has to have newer diesels in it, like a conversion from gas in the last 10 years and preferable Cummins. Family liked the lay out and the size.
 

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fighterpilot said:
The fuel system on the boat I looked at is 4 tanks. Attached is the fuel valve configuration. Port valve, front and aft tank, and a starboard valve front and aft tank. Also a valve for the Generator. I believe it is factory since i found a brochure for that boat in the archives and it mentioned four tanks. The owner was pretty straight forward with me so I can believe him when he indicated trim tabs were inadequate, particularly with fuel in aft tanks. As far as a boat builder turning out a boat that wasn't perfect it happens. Owner also noted when aft fuel present the side thru hulls were really close to the water. He put shut off valves on them. Tabs are small on this boat. Just on outer portion of the hull on each side.
I will still keep the boat on my list but it has to have newer diesels in it, like a conversion from gas in the last 10 years and preferable Cummins. Family liked the lay out and the size.
Click to expand...

I looked at the owners manual in the archives as well...confirm it has 4 tanks.

Did you investigate the boat here in SE Florida that I sent you the link on?

http://miami.craigslist.org/brw/boa/1520310784.html

I have pics that I can e-mail if you are interested.

John F.
 
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Sprink56 that listing had been removed by the author, so I didn't see it. Thanks anyway. There was one in Tampa Craigs list, but no lower helm.
 
I get it; I was assuming the mains were plumbed to all four tanks which would have been the "maze" I was referring to. But the mains are plumbed to only the fore and aft tanks, while the gen has two tanks dedicated for it.

Curious- do you know how much of the 400 gal is dedicated to the gen tanks? Honestly, I've never seen a boat with two tanks dedicated solely for the generator...
 
I suspect gen. draws from the aft tanks along with the engines. The owner said he only kept about 10 gal. in the aft tanks for the generator use and to avoid the bogging down from the weight if the tanks were full. Interesting.
 
fighterpilot said:
Regarding the fuel tanks, as I understand it, the boat has 4 tanks and the two rearmost tanks the owner didn't use, except for the gen. since the boat wanted to bog down with them filled. I agree it does appear that more tab would be benificial. One of my previous boats, only 29 ft. had tabs as big as ones one this boat. It appears there main function was to keep it trimmed level from side to side. In fact the owner of the boat I looked at said it needed much bigger tabs. He had thought about adding them or even adding some structure extending from the stern to help it get the bow down. He did that with a mainship and had the fastest mainship in town, so he said. I guess i could believe that. Anyway, I passed on that particular sea ray but am still looking. Thanks
Click to expand...

This is what I did on my 390...and it surely works!!! At cruise, with fair sea, I can pull the tabs all the way up :wink:

Strange arrangement of fuel tanks...but one dedicated tank for the genset is not a bad idea....
 
I own a 1986 39' sedan sportfish and I love it.I added an 8hp.thruster. my boat has large tabs and will plane. the 4X100 gal tanks are for long range cruising and the gen set can draw of the aft. tanks, i have 340 mercs w/462 hrs.
 
I took some pictures today. These are the mods I made some years ago on my 390.
Props are 4 blade Mikado 21" X 24" and shafts are 45mm (1.772")
With these addictions the boat rides much more flat without tabs and goes onto plane with minimal bow rise.
Maximum speed is now around 32 knots with CATs 375. (I'll check this again after I got rid of some 80 galls of water that were trapped under the cabin floor....)

DSCN0643.JPG


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