How much trim?

[harcos]

I read somewhere the maximum I am supposed to be able to run my leg up on my 4.3 Mercruiser Alpha Gen+, can anyone tell me or show me a link to where I can find the information. To be clear looking for how high I can trim the leg engine running when idling around the shallows.

 

[Chris1956]

You can trim a lot if motor stays at idle. Basically as long as prop and water intakes are covered.

At higher speed the outdrive must be more vertical, within the brackets of the outdrive, or the universal joints will start to fail.

 

[Bondo]

I read somewhere the maximum I am supposed to be able to run my leg up on my 4.3 Mercruiser Alpha Gen+, can anyone tell me or show me a link to where I can find the information. To be clear looking for how high I can trim the leg engine running when idling around the shallows.

Ayuh,.... Welcome Aboard,...... If the trim limit switch is workin', you can trim up til it stops,......
If you over-ride it, with the tilt switch, yer raising it into the tilt zone, which stresses the u-joints, 'n can possibly breach the bellows,....

 

[harcos]

@Chris1956 thank you I am just concerned with idling out of the shallow boat launch and wondering what the maximum height to idle ( less than 1000 rpm) without hurting anything was. When cruising I cannot overtrim as it porpoises before it clears the support brackets.
@Bondo, this boat only has one trim/tilt switch on the gearshift/throttle so unfortunately I can't rely on that.

 

[velociraptorfarmer]

@Chris1956 thank you I am just concerned with idling out of the shallow boat launch and wondering what the maximum height to idle ( less than 1000 rpm) without hurting anything was. When cruising I cannot overtrim as it porpoises before it clears the support brackets.
@Bondo, this boat only has one trim/tilt switch on the gearshift/throttle so unfortunately I can't rely on that.

Interested in this as well. I have a trim up/down switch, plus a separate up only tilt switch for trailering. I know you're not supposed to rev the crap out of it when tilted all the way up, but it'd be nice to be able to get a little more tilt than the limit of the trim switch while going in and out of shallows and beaching on sand bars. I just don't want to destroy the u-joints or bellows in the process.

 

[Scott06]

@Chris1956 thank you I am just concerned with idling out of the shallow boat launch and wondering what the maximum height to idle ( less than 1000 rpm) without hurting anything was. When cruising I cannot overtrim as it porpoises before it clears the support brackets.
@Bondo, this boat only has one trim/tilt switch on the gearshift/throttle so unfortunately I can't rely on that.

I have had several boats in the same shallow cove (23-27" deep at end of dock) for many years. So basically I am forced to use the trailer button to trim essentially all the way up (7/8 out or so) just to get it in and out of the hoist, plus 7 min of idle speed out to deeper water. Its a great sandy cove to be in just a PITA getting in and out.

This will do no harm if you are just above idle speed 900-1000 rpm max. Only when completely up did I ever get any u joint noise on my old boat (alpha gen one), gen 2 has no issue. U joints in old boat were 23 years old and a lot of hours when replaced. 300 hrs on new boat original non greaseable ujoints.

You should have an alpha gen two shifter with two detents on trim button for trim and then trailer (press past first trim stop). What shifter do you have ? If trim detent doesn't work your trim limit switch on gimbal ring is bad

 

[velociraptorfarmer]

You should have an alpha gen two shifter with two detents on trim button for trim and then trailer (press past first trim stop). What shifter do you have ? If trim detent doesn't work your trim limit switch on gimbal ring is bad

I do have 2 detents. The first that's the trim up/down rocker switch, which has a trim up stop that's at about 5/8-3/4 of full up on the gauge, then the second, separate trailer button that will tilt that last 1/4 up or so before hitting the full up limit.

Good to know about running at full tilt on idle. I knew you don't want to rev the **** out of it when full up, but man, coming into sand bars and shallow areas trimmed down as much as I was was nerve wracking. So many damn rocks around here randomly, and dragging the skeg in the sand before actually beaching the keel.

 

[Scott06]

I do have 2 detents. The first that's the trim up/down rocker switch, which has a trim up stop that's at about 5/8-3/4 of full up on the gauge, then the second, separate trailer button that will tilt that last 1/4 up or so before hitting the full up limit.

Good to know about running at full tilt on idle. I knew you don't want to rev the **** out of it when full up, but man, coming into sand bars and shallow areas trimmed down as much as I was was nerve wracking. So many damn rocks around here randomly, and dragging the skeg in the sand before actually beaching the keel.

A lot of folks will say don't run it in trailer range but I've been doing it for 40 years... and my neighbors too

 

[poconojoe]

I would make sure your trim limit switch is adjusted correctly first.

 

[harcos]

I have had several boats in the same shallow cove (23-27" deep at end of dock) for many years. So basically I am forced to use the trailer button to trim essentially all the way up (7/8 out or so) just to get it in and out of the hoist, plus 7 min of idle speed out to deeper water. Its a great sandy cove to be in just a PITA getting in and out.

This will do no harm if you are just above idle speed 900-1000 rpm max. Only when completely up did I ever get any u joint noise on my old boat (alpha gen one), gen 2 has no issue. U joints in old boat were 23 years old and a lot of hours when replaced. 300 hrs on new boat original non greaseable ujoints.

You should have an alpha gen two shifter with two detents on trim button for trim and then trailer (press past first trim stop). What shifter do you have ? If trim detent doesn't work your trim limit switch on gimbal ring is bad

I will have to check the shifter, when I got the boat it was a disaster and the leg wouldn't go up so I bypassed the limit switch to get it to lift and then set it so it doesn't kick out until all the way up, Maybe it is in the shifter, I will check and let you know. Thanks

 

[harringtondav]

@Chris1956 thank you I am just concerned with idling out of the shallow boat launch and wondering what the maximum height to idle ( less than 1000 rpm) without hurting anything was. When cruising I cannot overtrim as it porpoises before it clears the support brackets.
@Bondo, this boat only has one trim/tilt switch on the gearshift/throttle so unfortunately I can't rely on that.

At idle you can safely drive the boat with the trim up and not damage the drive. Your prop will come out of the water and stop moving you before you get the drive too high.
My previous Alpha II boat had a trim limit. I often overrode it when in shallow water. My new boat is a VP SX. No trim limit. Prop splash and lack of thrust tell me when I'm high enough. Under high speed power any prop will break loose and cavitate before it gets high enough to stress the drive.

 

[JimS123]

I had a trim gauge in the dash. With the boat out of the water on the trailer I trimmed up until the OD was just above the keel. Then noted the position on the gauge.

Surely, it was above the trim range, and into the tilt range.

At that position I could run over anything as long as the boat itself didn't hit the bottom.

The Owner's Manual (silly paperwork) said I could run up that high as long as the RPM didn't exceed XXX.

I ran that boat for 35 years at 1000 rpm on the sandbar every weekend and never hurt the U-joint or gimble bearing.

 

[harcos]

I had a trim gauge in the dash. With the boat out of the water on the trailer I trimmed up until the OD was just above the keel. Then noted the position on the gauge.

Surely, it was above the trim range, and into the tilt range.

At that position I could run over anything as long as the boat itself didn't hit the bottom.

The Owner's Manual (silly paperwork) said I could run up that high as long as the RPM didn't exceed XXX.

I ran that boat for 35 years at 1000 rpm on the sandbar every weekend and never hurt the U-joint or gimble bearing.

I don't have a manual, used boat so that is what I am doing this summer like you said under 1000rpm and I can hear it sound off if the drive is too high. I know I have a small leak in the bellows so this winter I will pull off the drive to change them and give a good inspection and that will tell me if I have done any damage. Thanks for the input.

 

[Scott06]

I don't have a manual, used boat so that is what I am doing this summer like you said under 1000rpm and I can hear it sound off if the drive is too high. I know I have a small leak in the bellows so this winter I will pull off the drive to change them and give a good inspection and that will tell me if I have done any damage. Thanks for the input.

The leaky bellow will do more damage than running it on trailer range

 

[harcos]

The leaky bellow will do more damage than running it on trailer range

I don't think so, its just a U-joint . If that was the case we couldn't/shouldn't drive our trucks in the rain. I will be able to verify in a few days as I ran it like that all summer and am going to pull it apart soon.

 

[airshot]

I do have 2 detents. The first that's the trim up/down rocker switch, which has a trim up stop that's at about 5/8-3/4 of full up on the gauge, then the second, separate trailer button that will tilt that last 1/4 up or so before hitting the full up limit.

Good to know about running at full tilt on idle. I knew you don't want to rev the **** out of it when full up, but man, coming into sand bars and shallow areas trimmed down as much as I was was nerve wracking. So many damn rocks around here randomly, and dragging the skeg in the sand before actually beaching the keel.

If your worried, just move everyone far forward so there is little weight in the stern, you would be surprised how much that raises that outdrive !!! I did that on my Islander many times and could run in 18" of water without extreme tilting of my outdrive.

 

[harringtondav]

I don't think so, its just a U-joint . If that was the case we couldn't/shouldn't drive our trucks in the rain. I will be able to verify in a few days as I ran it like that all summer and am going to pull it apart soon.

There are two U joints coupled with a cardan. Unlike automotive unis, your driveshaft unis stay submerged in a leaking bellows. Worse is what the water does to your gimbal bearing and outdrive gear yoke seal surfaces.
Recommendation is to pull the drive annually to verify a dry bellows. ....I'll go a couple three years with a new or replaced bellows before I start the annual check. Bellows replacements are relatively inexpensive compared to repairing the carnage from a wet driveshaft assembly.

 

[Scott06]

I don't think so, its just a U-joint . If that was the case we couldn't/shouldn't drive our trucks in the rain. I will be able to verify in a few days as I ran it like that all summer and am going to pull it apart soon.

Not really, see below

There are two U joints coupled with a cardan. Unlike automotive unis, your driveshaft unis stay submerged in a leaking bellows. Worse is what the water does to your gimbal bearing and outdrive gear yoke seal surfaces.
Recommendation is to pull the drive annually to verify a dry bellows. ....I'll go a couple three years with a new or replaced bellows before I start the annual check. Bellows replacements are relatively inexpensive compared to repairing the carnage from a wet driveshaft assembly.

exactly water gets in gimbal bearing and needle bearings in ujoints , rusts input shaft causing a leak… may work now but let that moisture corrode the bearings over the winter and it wont work next year.