lower unit thrust

[jmarty10]

Heres a dumb question. If you have youre drive set at trailer up position, would there be enough of thrust to power up onto the trailer?

The water was so shallow on Sunday that I literally had to start raising the unit to trailer up. I was trolling at idle speed. I hit the trailer but am freaking becasue I dont remember if I re-lowered my drive to get up on to the trailer. I think I lowered a little bit. I know the drive was definitlely not all the way up. I also know powering up is not good, but there really want any other way on Sunday due to ramp conditions.

 

[Fishermark]

Re: lower unit thrust

Heres a dumb question. If you have youre drive set at trailer up position, would there be enough of thrust to power up onto the trailer?

Don't know - but I doubt it. Definitely not a good idea however.

The water was so shallow on Sunday that I literally had to start raising the unit to trailer up. I was trolling at idle speed.

What drive are you talking about? Mercruiser? OMC? Volvo? I know that Mercruiser "allows" for slow speeds with the unit up higher than the typical trim limit... but I would not suggest going all the way up to the trailer position!

I also know powering up is not good, but there really want any other way on Sunday due to ramp conditions.

That's when you simply employ your wench. Most ramps don't like people powering on anyway as it blows out the end of the ramp area.

 

[jmarty10]

Re: lower unit thrust

Sorry - its a merc. alpha one

 

[RepoMan207]

Re: lower unit thrust

you should never have your trim in "Trailer" position while your motor is running. trailer position is for just that, for when you already have it loaded on the trailer for transport. There is a reason why the trim button bottoms out at a certain point and doesn't continue to the trailer position. It will ruin your U joints and Gimbel bearing very quickly.

What your referring to is Power Loading. Do you have a bunk or roller style trailer? If it is a bunk trailer you need to back in deeper for easier loading.

 

[jmarty10]

Re: lower unit thrust

Repo - the merc manual says you can run at trailer high but no higher than 1200 rpm or you can cause severe damage. I was trolling at about 600 rpm when i hit the bunks. Even though I was in trailer high mode, I dont think I was all the way up in trailer high. I'm just freaking becasue I dont specifically remember how low I lowered the unit. But, for my peace of mind, I'm thinking if I had enough thrust to get up the bunks, I must have had the unit lowered. Or at least I'm hoping

 

[Maclin]

Re: lower unit thrust

If you were up too high and hit the throttle any you would have heard the props back there.....

 

[jmarty10]

Re: lower unit thrust

Macklin - please explain? Water was splashing all over from the thrust. It was very loud out there as it was the middle of the day and crowede

 

[RepoMan207]

Re: lower unit thrust

Repo - the merc manual says you can run at trailer high but no higher than 1200 rpm or you can cause severe damage. I was trolling at about 600 rpm when i hit the bunks. Even though I was in trailer high mode, I dont think I was all the way up in trailer high. I'm just freaking becasue I dont specifically remember how low I lowered the unit. But, for my peace of mind, I'm thinking if I had enough thrust to get up the bunks, I must have had the unit lowered. Or at least I'm hoping

.....really. Good to know. My current Bravo drive says not to run it all, and the mechanic I took for a test drive on my old boat (which had an alpha drive) almost had a heart attack when I started my boat in that position. Granted that was an older boat.

I too have a bunk trailer. I drive on at about half trim when loading, and it's simply a depth concern, not a thrust thing. To your concern...I guess you would have to take into consideration prior momentum and depth of the bunks, but I am pretty sure even from a stand still position at trailer height that you could get enough thrust to load.....minus any damage of coarse.

I understand you had other factors that day, but I would recommend backing your trailer in deeper whenever possible. I submerge the top of my fenders 2" - 3". I barley touch the bunks in the rear if at all, instead the hull makes contact about half way up the bunks, I let off the throttle and the momentum takes it the rest of the way and it "sits" into the bunks fully just as I come to the bow roller. Once I am in the bow roller (when I have assistance) or close to it (when I am solo).....(I have a 24' cuddy with a Fountain type bow, so I can't see where the bow is in relation to the roller from the helm) I shut her down and hook up the winch and crank her in.

When you launch your boat next time, back in until the boat just starts to float in the stern, then take note of how deep you are in relation to your trailer. Maybe it's just me, but thats were I have found my sweet spot for loading and unloading even on windy days.

Happy boating.

 

[jmarty10]

Re: lower unit thrust

Well - I guess I'm holding my breath now. Next time out, how will I know if I fried u-joints, gimbal bearing or anything else. Anything to check before or listen to while in the water?

 

[bigskiohio]

Re: lower unit thrust

i run mine high up in shallow water at idle to 1000rpm .my original merc manual says it is okay. I run it so prop is just below surface pointing back more the up.
if i hit any ting at that speed it hits the skeg and rides over it as it did this past weekend.

 

[Bondo]

Re: lower unit thrust

I also know powering up is not good, but there really want any other way on Sunday due to ramp conditions.

Ayuh,.... Like What,..??

 

[RepoMan207]

Re: lower unit thrust

i run mine high up in shallow water at idle to 1000rpm .my original merc manual says it is okay. I run it so prop is just below surface pointing back more the up.
if i hit any ting at that speed it hits the skeg and rides over it as it did this past weekend.

There is a diffrence between the trim being all the way up, and the trailer postion.

Well - I guess I'm holding my breath now. Next time out, how will I know if I fried u-joints, gimbal bearing or anything else. Anything to check before or listen to while in the water?

I wouldn't worry to much at this point. at worst you would have caused some premature wear, but chances are you would of heard alot of racket going on back there and no movement afterwords. If you hear any knocking or clicking sounds coming from the drive / transom area during your next run....it would be advisable to get it serviced right away. When they go, it usually takes other things with it...usually more expensive things at that.

 

[wca_tim]

Re: lower unit thrust

I know one thing... it'll have plenty of thrust to drive the back end of the boat down... making it harder to get up on the trailer.

 

[Maclin]

Re: lower unit thrust

Macklin - please explain? Water was splashing all over from the thrust. It was very loud out there as it was the middle of the day and crowede

When I have mine up quite a ways, too far really, I can tell right away because it just sounds way different.

 

[RepoMan207]

Re: lower unit thrust

When I have mine up quite a ways, too far really, I can tell right away because it just sounds way different.

Not to mention the massive bubbles at your stern.

 

[RepoMan207]

Re: lower unit thrust

i run mine high up in shallow water at idle to 1000rpm .my original merc manual says it is okay. I run it so prop is just below surface pointing back more the up.
if i hit any ting at that speed it hits the skeg and rides over it as it did this past weekend.

FYI.......I did some searching on the subject. This is what is posted in all the mercury Bravo's & Aplha's out drive service manuals that I could find. They very in wording from time to time, but all have the same statement.

 

[45Auto]

Re: lower unit thrust

You probably didn't affect anything for the few minutes you ran it. I have a neighbor that flushes his 5 or 6 year old Alpha in the full-up trailer position almost every week. Prop is pointing almost straight up. Runs it for about 10 minutes each time. It never has been off the boat, never had the alignment checked, still all original u-joints, bellows, gimbal bearing, etc. I told him it wasn't good for his u-joints, he lowered it while running for a few weeks then went back to his old way.

The reason for the Mercruiser warning statement about running in the up position is because the gimbal ring support flanges (the "ears" on the gimbal ring) are designed to take all the sideloads from the drive. If the drive is trimmed up above the support flanges, all the side loads are applied to the gimbal ring through the gimbal bellhousing (the "helmet") pivot pins. The bellhousing and gimbal ring are NOT designed to take a side load at these locations and either one could break (thus causing "severe damage" to the drive unit ....).

I very seriously doubt if you put any significant side loads on the drive while trailering, and while it's definitely not good for your u-joints, I doubt if you did anything at all to the drive.

 

[jmarty10]

Re: lower unit thrust

Thanks for the replys all. I think I'm done boating until the river gets a little higher. Its just too risky now. Anyways 45 auto, I'm real sure I was not fully up in the trailer high position. I think the drive/prop was still beneath the stern of the boat. I didnt hear any grinding or anything different while thrusting up the trailer. When I have my muffs on in the driveway, the unit is lowered to where the skeg almost hits the driveway. My drive was lower than that while powering up the trailer on Sunday.

 

[cr2k]

Re: lower unit thrust

Like someone said earlier, Use your wench and if she won't help try your winch.

I always back my trailer in deep enough to wet the bunks then pull out to the right depth for my boat to load. Wet bunks slide much easier.

If you can't get your trailer in any deeper it must be time to wait for the water to rise.