280 Drive Trim & Trim Tabs

N

NorthvilleJim

New Member
Mar 14, 2008
88
Michigan
Boat Info
280 Sundancer 2007
Engines
Twin 4.3 L Mercruiser w/ Alpha drives
For anyone that has a 280 Sundancer or comparable with twin screws, do you ever play with the drive trim or the trim tabs?

A buddy of mine has told me that I should be able to approve fuel economy by trimming the drives up about 5 degrees (1 or 2 notches on the gage). I tried that for a few minutes on 3 hour trip a few weeks ago and felt like I was losing power, so I went back to have the drives all the way down. Would be interested in hearing experienced opinions on the optimum drive trim for fuel economy. I burned about 65 gallons of gas on a 3 hour cruise. Does that sound about right? :huh:

Also, I realize that any use of the trim tabs will probably hurt fuel economy, but when do you use the trim tabs? I seldom ever use mine.
 
The only time I use my trim tabs is if I have 6-8 people and want to get up to cruising speed around 24-25 MPH and 3200-2400 RPM. Once I get up to cruising speed, I retract them. As far as trimming the drive, I get up to cruising speed and bump the drives up a little bit. I have analog gauges so can't tell you what step that might be. I dont think you should have been loosing power when you trim the drives up. What RPM were you at?

As for the 65 gallons of gas, what speed and RPM were you running and how far did you get?

Glenn
 
Sun Chaser said:
The only time I use my trim tabs is if I have 6-8 people and want to get up to cruising speed around 24-25 MPH and 3200-2400 RPM. Once I get up to cruising speed, I retract them. As far as trimming the drive, I get up to cruising speed and bump the drives up a little bit. I have analog gauges so can't tell you what step that might be. I dont think you should have been loosing power when you trim the drives up. What RPM were you at?

As for the 65 gallons of gas, what speed and RPM were you running and how far did you get?

Glenn
Click to expand...

I was cruising at about 3400-3500 RPM. GPS speed was about 30 MPH. I had 4 people on board.
 
I only use the tabs to get up on plane with a full load or to adjust lean with cruising on a windy day.

As far trimming the drives up, 5% might be too much. I would use your Smartcraft readings first, then you'll get an idea of how they should read on the analog gauge. The Smartcraft trim scale should be:

1-10 for operation
10-25 for trailering

This is a fairly large boat and doesn't require much engine trim. My normal operating trim reads as 3 on the 1-10 operating scale on full plane. Any more than 4 and I start to hear the drive whine and lose grip.

65 gallons sounds about right for a continuous 3 hour cruise at 30+ mph. (I know..... makes you wish you had a bigger gas tank in that 280). : )

Hope this helps.

Mike
 
Last edited:
The only time I use my trim tabs is to get up on plane or if I have several people on the boat and I need to level it out.

As far as trimming the outdrives, I do that as well. I'm not sure what the setting is right now sitting at my desk, but I know that after I get up on plane, I hit both thumb switchs on the throttle 3 quick times and that gets me where I want to be.

I can't really help you on the gas mileage because I ussually only take short little trips to a cove on the lake.

Hope this helps.
 
MExcelsior said:
I only use the tabs to get up on plane with a full load or to adjust lean with cruising on a windy day.

As far trimming the drives up, 5% might be too much. I would use your Smartcraft readings first, then you'll get an idea of how they should read on the analog gauge. The Smartcraft trim scale should be:

1-10 for operation
10-25 for trailering

This is a fairly large boat and doesn't require much engine trim. My normal operating trim reads as 3 on the 1-10 operating scale on full plane. Any more than 4 and I start to hear the drive whine and lose grip.

65 gallons sounds about right for a continuous 3 hour cruise at 30+ mph. (I know..... makes you wish you had a bigger gas tank in that 280). : )

Hope this helps.

Mike
Click to expand...

+1
Very helpful. Your comment about losing grip describes what it felt like when I trimmed up. Probably went too far. I'll try it again on my next trip. Yes, a bigger tank would be nice for longer trips.
 
The only times I trim my drives are either when I am going into the shallow area to raft off, putting the boat on the trailer or over 40mph(anything slower and it loses grip). I use the tabs depending on the wind and canvas configuration.
 
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