Outdrive Trimming Technique

Flytrade

Active Member
Feb 20, 2018
302
Bradenton, FL
Boat Info
2006 320 Sundancer
Engines
Twin 6.2L Mercruiser
I don't seem to have a very good technique for trimming the outdrive on my 260 Sundancer. I would like to know your trimming technique for best cruise performance.

As a data point on my boat. I have a Mag 350 engine w duo-prop. Normal cruise is 3900 rpm at 25 mph, and the best I can tell I'm getting about 1.8 mpg. If you believe the trim gauge, it's about 3 units below center. However, when I take the boat out of the water, it appears the outdrive has a lot of up trim.
 
Your gauge maybe be out of whack. Best way to trim is by your "seat 'o the pants meter" and/or looking at the spray coming off the hull side. There's no one best way to trim it, though - as conditions will dictate where the drive is to be set for optimal running. Mid to upper 3,000RPM range will typically result in the best efficiency on plane.
 
I have the same hull and power package.

I start with the drive all the way down. As I come up on plain, I start to trim up the drive a little. Once up on plane I've found the most efficient position is just about 1/2 way up, maybe a touch more. That's assuming calm seas. Efficiency / comfort and trim settings change with higher seas.

Dennis has it right - you can feel the performance of the boat. I also use my GPS speed and adjust the trim and monitor the results. You may want to reset the outdrive trim gauge via your SmartCraft dials.

My current best "feeling" cruise is 27 mph at 3900 rpm. Top speed is a touch over 36. But I had my bottom blasted and epoxy coated in the spring so it's nice and smooth. Before that it was pretty crusty with old paint and the performance was not good.
 
Brad... just an FYI, your hull is a newer design than the '99-'04 260DA. Yours is very similar to the '05-'09 260DA. Your boat is a good bit heavier than the earlier version.
 
Although we don’t have the same boat, I too use the “seat of the pants-o-meter” to adjust trim.

I find that once I’m up on plane, 3 short clicks on the “up” button is the sweet spot.

I can hear that the engine sounds smoother and I can see the bow is higher. The spray comes from a point further aft, which give a dryer ride for the bow passengers.
 
Brad... just an FYI, your hull is a newer design than the '99-'04 260DA. Yours is very similar to the '05-'09 260DA. Your boat is a good bit heavier than the earlier version.

Oops, my mistake. I thought the change over for the 260DA was '03-'04.
 
Trim tabs down, Alpha's down and in the locked position, throttle up to 3,000 rpm's and wait for the boat to come up on plane. Once up on plane, I pull the trim tabs all the way out and adjust for left/right balance. Then I tap the Alpha's out just for a blip or two. My trim gauges are currently not working so that's a plus. Then I add trim tab back in to achieve the best cruising speed for that given throttle setting. 3,000 to 3,300 usually is around 25 to 28 mph.
 
Thank you for all your responses. I'm taking the boat out in a few days, and I'll try your different techniques. My initial thoughts, after reading the above, is that I'm using too much up trim.
 
I don’t have 260 but 3900 rpm sounds way high for cruise rpm and I definitely can’t see that as the most efficient rpm. My fuel data skyrockets after 3600 rpm. I prefer to cruise at 3300. Most will tell you small blocks like 3000-3200 as most efficient.
 
You guys have guts to trim halfway while on plane. When I had outdrives I never went above 1/4 on plane. To much anything beyond that puts a tremendous amount of torque on the u-joints and gimbal bearing. Costly repairs down the road.
 
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