Help! How to correctly trim and tilt OMC 800 Stringer

[Costello]

I just bought a 1979 deck boat with 185 hp OMC (I/O)--800 series Stringer. I had my "boat guy" look it over before I dropped it in the water. He replaced the trim and tilt motor and gave it a tune up. He told me that the lower unit should either be up (trailering) or down (boating)--no in between, otherwise I will do serious damage inside. The lower unit moves very quickly to either position. Also, there is a second switch that lowers and raises the lower unit by 4 to 6 inches (I've never seen that before).<br /><br />So, I followed his advice. Living on a shallow lake, I quickly tore up my prop. Not only that, but I had no way to adjust the boat at higher speeds--the front end was perched too high.<br /><br />On my previous boat, I could adjust the trim and tilt accordingly.<br /><br />Am I doing something wrong? Thanks for the help!

 

[boaterntexas]

Re: Help! How to correctly trim and tilt OMC 800 Stringer

Unless he did a shoddy job on your trim system I see no reason you would trim out while underway, you do want to be carefull as to how high you trim it with the motor running.. My boats, I typically trim all the way down to get strated, then trimm up till I fid a good comfortable spot.<br /> The switch which raises it 4 to 6 inches may just be a preset switch that the prevois owner used, me when I'm pulling a skier or really want a good hole shoot I will trim up a bit before I take off then trim down. PS I really have no clue what I'm talkign about so don't listen to me, I run mercs.<br /><br /> Thomas

 

[tmclendon]

Re: Help! How to correctly trim and tilt OMC 800 Stringer

You have seperate TRIM and TILT switches, and indeed they control very different systems.<br /><br />Your "boat guy" friend is partly correct about the TILT, you should always have it all the way down when boating (You can run at idle with it tilted up some, as for getting on and off the trailer (or sand bar!), but never exceed 1000 RPM or so with the tilt not fully down). When it's on the trailer, it does not need to be ALL the way up, there is nothing magical about going as far up as possible; I usually keep mine about 60 degrees up, plenty of room to clear any road obstacles. On the other hand, it doesn't HURT anything to have it all the way up, unless it hits the transom...<br /><br />The trim, on the other hand, adjusts the angle of the WHOLE engine/outdrive assembly, therby keeping the drivetrain in allignment between the motor and the outdrive, so you can go full speed at any trim setting. That's why you have that giant rubber boot on the transom, to allow the whole thing to move up and down. You can use the trim at any time and any speed.<br /><br />By the way, you're lucky the trim/tilt works that well, theses systems are notorious for having problems...<br /><br />Hope this helps!<br /><br />Tom

 

[McKenzie]

Re: Help! How to correctly trim and tilt OMC 800 Stringer

The previous owner was right, if you use tilt to adjust your boats handling, you will ruin the gears in the outdrive. I believe you can use tilt under 800 rpms, so you can idle into your dock or beach, etc. But above 800, run in full down tilt or you risk wearing the gears down. The trim raises and lower the engine in sync with the outdrive so the drive components stay in line and don't wear out, thus you can adjust this however and whenever you want. If you don't like how the boat handles, change the weight distribution and/or see if hydrofoils help. Trim tabs would probably help a lot. As for the prop, disposable blades might be an option, but if you tear up a prop that fast, it probably isnt cost effective.

 

[McKenzie]

Re: Help! How to correctly trim and tilt OMC 800 Stringer

Oops, snake bit beat me to it. He's right that 1000rpms is recommended, but i'd only run 800rpms to be safe.

 

[Costello]

Re: Help! How to correctly trim and tilt OMC 800 Stringer

Thanks for the valuable info. If anyone else wants to chime in, please do.<br /><br />What are trim tabs? <br /><br />Also, I just bought a stainless steel prop to replace my chewed up aluminum one. Should I be concerned about damaging the shaft if the prop hits the bottom of the lake? (I can't afford disposable props!) Will I notice much difference going from a 19 pitch to a 21 pitch prop?<br /><br />I guess a fish/depth finder wouldn't hurt, too. Any recommendations on make and model?<br /><br />As always, you guys are the best!

 

[7-up]

Re: Help! How to correctly trim and tilt OMC 800 Stringer

If you use a s/s prop and you hit a rock, the prop will be fine but the shaft may bend. I would stick with aluminum and try to avoid hitting bottom. trim up in the low spots

 

[McKenzie]

Re: Help! How to correctly trim and tilt OMC 800 Stringer

The blades for disposable props are $20 around here, about $80 for the hub. If you need to replace a blade or two during a season, i think it would be cost effective. At least more cost effective than a prop shaft and seals will cost you because of a s/s prop. Trim tabs are flat pieces of metal that are hinged at the back of the boat. they are electrically controlled to adjust the angle of the "tab" in relation to the hull. The reason i suggested them was you said the boat's handling feels weird and trim tabs can compensate for that (to an extent). They won't however do anything to keep your prop off the bottom of the lake. Here are some trim tabs examples. West Marine