Merc trim problem(maybe/maybe not)

[Speedwagon]

It's an 85 Merc I/O, I believe a 170 engine. Don't think it's an alpha one outdrive, as I didn't see the alpha one on it(friends boat).<br /><br />When I trim in all the way, while under power, the boat doesn't feel right to me. It almost feels like the outdrive is starting to go under the boat a little bit, and push the rear up. Has kind of a bogged down sound to the engine at this point.<br /><br />And, when I trim it up all the way(not trailer), it doesn't seem to be up all that high. At least, I can't clear some of the shallow spots in the river without hitting.<br /><br />The trim indicator goes from all the way in, to just over half at the stop. I've never been real sure on how these gauges are supposed to read though.<br /><br />So is this setup properly? Or does it need some adjusting?

 

[Gary H NC]

Re: Merc trim problem(maybe/maybe not)

When you trim in all the way you are feeling bow steer.<br />Trimming up all the way is not meant to lift it high enough to miss rocks or the bottom.<br /><br />Trim indicator rarely is ever accurate.<br /><br />It's probably workin ok just the trim guage is off.

 

[Speedwagon]

Re: Merc trim problem(maybe/maybe not)

So what is the UP on a trim gauge meant to show? Trailer position, or maximum trim up before trailer position?

 

[Don S]

Re: Merc trim problem(maybe/maybe not)

Full up on the gauge means trailer position.<br />The drive is equiped with trim so it can be trimmed to best position no matter what or how the boat is loaded.<br />Trim the drive up so you get best speed and best rpm, if you trim too high, the rpm will increase, and the speed decrease. Trim it down some, so you get best ride, speed and rpm. It's usually done more by feel than trim gauge once you get experince with using it.<br /><br />Here is a link to the owners manual for a Mercruiser that shows the trim usage. Look at page 32 on power trim.<br /> http://www.boatfix.com/merc/Owner/gas/86017101.pdf