Power trim and tilt vs underwater objects?

TinBoats.net

Help Support TinBoats.net:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

ktoelke54

Well-known member
Joined
Sep 5, 2016
Messages
149
Reaction score
1
I’m considering a new outboard purchase in the 25 hp range (maybe the new Yamaha) and was wondering about power trim and tilt and river running. I do a lot of my boating on a river where shallow water and rocks are the norm. I have been using 2 strokes, a 15 and a 25, which tilt ok by hand. I use a prop protector and run with the motor unlatched. When I do bump a rock the motor just kicks up, no damage to the prop, skeg or lower unit. Mostly I’m going slow when this happens and it’s not that traumatic. But occasionally I’ll bump one at full tilt and as much of a shock as it is I have not, as of yet, incurred and damage.

So if to save my old back, I bought a new 25 hp with power trim and tilt, do you think it would work for me under these conditions?
 
There is a bypass circuit/path in hydraulic trim systems for that very reason, but we’d need Pappy to chime in and advise if they are as responsive to strikes as your other motors were. My gut tells me ‘no’, but that’s a guesstimate.

Now I did hit a log w/ a V6 OB once whilst up cruising on plane and that motor sure bounced up (and suffered no damage, if you can believe it!), but either way ... there’s still a lot of metal in motion and I’d like to see what an expert thought.

TurboTodd here is really sharp on motors too, so maybe he’ll see this post too.
 
I live in/run in rocky/stumpy areas all my life. I use my boat for hunting out of as much as fishing and do a lot of messing around at night coon hunting. This requires a bunch of tooling around in extremely shallow water. Your trim/tilt will not move. It is either going to tear the transom or lower unit up in an extreme strike.

That being said I have never torn a LU or transom out, but I have been the owner of several new props. I made this contraption and it solved my issues. It is very similar to the Macs River Runner with a few mods.
propguard.jpg
 
nccatfisher said:
I live in/run in rocky/stumpy areas all my life. I use my boat for hunting out of as much as fishing and do a lot of messing around at night coon hunting. This requires a bunch of tooling around in extremely shallow water. Your trim/tilt will not move. It is either going to tear the transom or lower unit up in an extreme strike.

That being said I have never torn a LU or transom out, but I have been the owner of several new props. I made this contraption and it solved my issues. It is very similar to the Macs River Runner with a few mods.

I use a Mac’s River Runner, that is what I thought you had till I took a closer look. Yours looks even more heavy-duty.


Sent from my iPad using Tapatalk
 
What you want is a breakaway plate which is a jackplate that pivots at the top when you hit an obstacle.A proper breakaway plate should have a safety strap or some type mechanism limiting its travel.I have hit a log at speed without power-trim and the lower unit swung up nearly vertical breaking the transom bracket.It is not inconceivable that the spinning propeller could end up inside the boat.I now have a length of heavy nylon webbing around the leg secured to the transom.Not sure if the release valve in a power trim would prevent "rapid deceleration" if you hit something big in a light boat.m.w.
 
ktoelke54 said:
nccatfisher said:
I live in/run in rocky/stumpy areas all my life. I use my boat for hunting out of as much as fishing and do a lot of messing around at night coon hunting. This requires a bunch of tooling around in extremely shallow water. Your trim/tilt will not move. It is either going to tear the transom or lower unit up in an extreme strike.

That being said I have never torn a LU or transom out, but I have been the owner of several new props. I made this contraption and it solved my issues. It is very similar to the Macs River Runner with a few mods.
propguard.jpg

I use a Mac’s River Runner, that is what I thought you had till I took a closer look. Yours looks even more heavy-duty.


Sent from my iPad using Tapatalk
It is heavier but has larger holes in the front to allow less resistance. It was a trial and error type of thing. It has served me well on several motors over the years.
 
If the piston in the trim ram is equipped with impact valving the engine will indeed swing up and over an object. Some systems will not return to the run position afterward.
Having not looked at the new system I can only offer this.....
Manufacturers, while designing a new outboard, normally do impact testing until destruction. To make a long story short the parts of the engine that allow tilting, trimming, and clamping to a transom are designed to do their job and also break in a pre-determined order for safety.
Of course the testing is done in controlled circumstances and your results will most certainly vary in the real world. WOT operation and a serious hit? All bets are usually off !
This brought up some fun memories!
I have done factory destructive testing on both outboard and stern drive product. Testing was done on-water at precise trim angles and speeds that were progressively faster and more destructive. We did the testing while driving inside a protective cage built into the floor of the boat. Drive units were always tied to a rope and flotation marker which exited with the drive when it finally started breaking completely off. Outboards were also attached to a rope and marker but were usually held by the steering cable or cables after they broke off. Outboards at high speeds did come in the boat and back out on more than one occasion vs. never for a stern drive. No matter how good you think you are at running the boats for this testing the boat will almost always hook to the left when the drive or outboard breaks off and you will always try and steer it straight.......with no engine or drive to do it with! :roll:
Back in my test driving days I did have two V6 200/235hp outboards break off (two separate occasions) and come in the boat with me with no protective cage. One left prop marks as it slammed down that were less than a foot away from the front of my seat. Both engines exited as fast as they came in and were found at the end of the steering cables under the boats.
 
There are products like this. They are jack plates designed to swing up. Would provide the break away you are looking for plus gain set back vertical adjustment so you can raise the lower unit up as much as possible.

https://www.vancemfg.com/product-p/jpl9638-gen3.htm

JPL9638-GEN3-2T.jpg
 
Pappy said:
No matter how good you think you are at running the boats for this testing the boat will almost always hook to the left when the drive or outboard breaks off and you will always try and steer it straight.......with no engine or drive to do it with! :roll:
Grab that wheel ... and turn it harder!

Pappy said:
Back in my test driving days I did have two V6 200/235hp outboards break off (two separate occasions) and come in the boat with me with no protective cage. One left prop marks as it slammed down that were less than a foot away from the front of my seat.
O M G ... glad you’re still here to talk about it ...
 
ktoelke54 said:
wmk0002 said:
There are products like this. They are jack plates designed to swing up. Would provide the break away you are looking for plus gain set back vertical adjustment so you can raise the lower unit up as much as possible.

https://www.vancemfg.com/product-p/jpl9638-gen3.htm

JPL9638-GEN3-2T.jpg

Thanks, that looks like it would work.


Sent from my iPhone using Tapatalk

Good luck. Don't personally have any experience with that product but recently bought their mini jacker and it is a very nicely made jack plate. Great quality and considerably cheaper than others. Bet you can find some more info on the duck hunting forums out there.
 
The yamaha will kick up but it takes a pretty good lick. BTDT.

In order to get power tilt on the Yamaha, you have to order/buy the motor as a remote steer, and have them install the tiller kit-which adds expense to the motor. I hate how Yamaha does that with the smaller motors. I may be in the market for a power tilt 15 or 20 but I gotta look into it more. It'd be for my dad's boat that he just bought.

The newest version of the 25 tilts as easy as the old 2 stroke 25. I've got a 2018 25 and had a 2007 25 (2 stroke)-and there isn't much difference in manual tilt effort.

You can run a kickup plate such as shown above but some of them don't come with a chain, so you'll have to add one. That or a cable of some sort. The good thing about the kickup is that it moves the motor back about 5", which allows you to raise the motor, which gives you some more clearance for running skinny. I JUST got in from running a skinny river; didn't hit anything, caught plenty. I have my motor raised on the transom about an inch and a half with a wood spacer. Every little bit helps on certain waterways. It was so bad this morning that I was able to run on plane the entire 5.1 miles to the hole, but going back....water dropped about 2', had to get out & pull the boat over a gravel bar manually. Wasn't a big deal; just enough to float it over without me in the boat, about 4-5" deep. Sure was cold though.
 
If the piston in the trim ram is equipped with impact valving the engine will indeed swing up and over an object. Some systems will not return to the run position afterward.
Having not looked at the new system I can only offer this.....
Manufacturers, while designing a new outboard, normally do impact testing until destruction. To make a long story short the parts of the engine that allow tilting, trimming, and clamping to a transom are designed to do their job and also break in a pre-determined order for safety.
Of course the testing is done in controlled circumstances and your results will most certainly vary in the real world. WOT operation and a serious hit? All bets are usually off !
This brought up some fun memories!
I have done factory destructive testing on both outboard and stern drive product. Testing was done on-water at precise trim angles and speeds that were progressively faster and more destructive. We did the testing while driving inside a protective cage built into the floor of the boat. Drive units were always tied to a rope and flotation marker which exited with the drive when it finally started breaking completely off. Outboards were also attached to a rope and marker but were usually held by the steering cable or cables after they broke off. Outboards at high speeds did come in the boat and back out on more than one occasion vs. never for a stern drive. No matter how good you think you are at running the boats for this testing the boat will almost always hook to the left when the drive or outboard breaks off and you will always try and steer it straight.......with no engine or drive to do it with! :roll:
Back in my test driving days I did have two V6 200/235hp outboards break off (two separate occasions) and come in the boat with me with no protective cage. One left prop marks as it slammed down that were less than a foot away from the front of my seat. Both engines exited as fast as they came in and were found at the end of the steering cables under the boats.
Great and interesting remarks. Did you ever find a solution to preventing the motors from entering the boats when whacking something at speed causing the bypass valve to allow the engines to come flying up into the boats? It seems it would be much safer to let the lower units sheer off, or at least have some sort of shock absorber built in that would absorb the shock and prevent the outboard from slamming the transom so hard on the upswing, that is snaps off and potentially enters into the bilge area of the boat. I run an MFS50A Tohatsu Tiller on a jack plate, and there is a clearance issue whereby the motor can only be trimmed up about 70% before the tiller arm hits the top of the transom. If I were to hit something at speed, it sounds like the motor might slam up, break the tiller off, and I'd be left with a screaming motor and no way to control it or shut it down. Any ideas/thoughts on how to resolve, short of removing the jack-plate?
 
Great and interesting remarks. Did you ever find a solution to preventing the motors from entering the boats when whacking something at speed causing the bypass valve to allow the engines to come flying up into the boats? It seems it would be much safer to let the lower units sheer off, or at least have some sort of shock absorber built in that would absorb the shock and prevent the outboard from slamming the transom so hard on the upswing, that is snaps off and potentially enters into the bilge area of the boat. I run an MFS50A Tohatsu Tiller on a jack plate, and there is a clearance issue whereby the motor can only be trimmed up about 70% before the tiller arm hits the top of the transom. If I were to hit something at speed, it sounds like the motor might slam up, break the tiller off, and I'd be left with a screaming motor and no way to control it or shut it down. Any ideas/thoughts on how to resolve, short of removing the jack-plate?

Vance JPL9620 5 1/2'' Setback "Vance Manual Kick & Jack"​

Ive also seen people stack a regular kick up(breakway) plate to a jackplate....sits ya back a ways, better have a long tiller handle.
Theres other brands of kick up plates , some only have 3/4"s of set back.
 
I would read your manual. Mine even has some protection when inrverse.
 

Attachments

  • Screenshot_20240729_164012_Samsung Notes~2.jpg
    Screenshot_20240729_164012_Samsung Notes~2.jpg
    50.2 KB
  • Screenshot_20240729_164255_Samsung Notes.jpg
    Screenshot_20240729_164255_Samsung Notes.jpg
    68 KB
Since your buying new is a jet out of the question? I know the loss of power is a consideration and weight if you decide to bump up the HP. Most guys I know that run water like you describe run jets.
 
Quite a few years ago a buddy and I were following each other most of the day out fishing, we ran further out in the salt then usually one day, and a storm was coming on fast so we figured we'd best get back to the dock or at least back to creek where we launched from.

We were going all out trying to stay ahead of the storm, already getting pelted with hail as we turned and headed up river. About half way up the river there's a few areas that look like open water but are not, the main river winds around to the left, and the straight away 'open' water is only a few inches deep at low tide. I was following my buddy who was running an older 18ft Starcraft with an old 65hp electric shift motor, I had a newer modified V hull bass boat with a newer 60hp on it. I was lighter and faster so I let him set the pace.

As we rounded the first bend in the river I saw his boat do sort of a hop on the water and we saw the prop come out of the water for bit then he drifted to stop still trying to figure out why he had no forward momentum. But hat time it was pouring rain and starting to really hail. He tried to pull the motor up but it wouldn't move. He also said the fuel tank, which sat under the back of the boat was now hitting the bottom of the splash tray. I pulled up, tied off to his boat and just towed him the rest of the way.

The rain had either passed or we got out from under the storm as we got back to the ramp. He gets his truck and trailer, and one of the guys with us jumped out and led his boat to the trailer figuring that it may have an issue getting up the ramp since the motor wouldn't tilt.

As he pulled the boat up the ramp we could see how bad it was. His prop was gone, which at first I figured it wasn't such a big deal. The skeg was still intact.

I got my truck, loaded my boat and walked over to see about getting his motor up so he could tow it home.
It too a second but I did a double take and realized not only was the prop gone, the shaft was gone too, leaving a hole where the shave sued to be. I could stick my finger through the seal and feel that the shaft was there but broke off just beyond the bearing.

Closer inspection showed that the tilt pin, (manual tilt) was bent. It bent so much so that the release lever didn't have the leverage to disengage the pawls. A few taps with the hammer and it was free and he was able to strap it in the up position
With the motor up, and boat done draining we got a good look at the bottom of the boat and the bottom was dented upward about a foot on mostly on the right side leaving the imprint of the three rear transom gusset braces showing through the bottom of the hull. It wasn't until he went and found a parts motor for a good used lower unit that he realized that the whole motor bracket was cracked at the throat of both clamps. What ever he hit made first contact about 3ft forward of the transom just off to the right of dead center.

At that point he just walked away and went an found another boat.

A couple of us went back the next morning in my boat at low tide to see if we could see what he hit, but there was nothing there, then as we went further down stream we found an 8ft log that had washed up against someone's private dock with a prop embedded in it and a massive chunk missing.
The log was a foot in diameter and super old looking when we tied onto to it figuring we'd bring him the souvenir we could barely move with it in tow being that it floated beneath the surface, so we beached the log and pounded the prop and bent prop shaft out of the wood and went home. It hit so hard that the one prop blade was half torn off the hub, but the rest were undamaged. The shaft though looked like it had already been cracked being discolored about half way through the break. It also had a bit of twist in it just beyond the splines.

He sold the boat no clue whether the buyer fixed it or not but the motor was just parts. A closer look at the drive shaft also showed the four splines were twisted nearly 1/4 turn.

In later years, others have hit logs like that, there. Many year ago it was known for stumps in that area where they had cleared out trees and moved the river over a few thousand feet to build a bridge that never happened way back in the 1920's or so. After years of dredging most of the stumps are gone but logs even telephone poles are a real issue. I've bumped over a few but never at high speed like that. (He was probably doing about 35 or so when he hit that log.

His next boat was glass, which turned out to be a bad choice, about four years later he hit a log in another river that was stuck in the mud. He was passing someone outside the marked channel and hit the end of the log at 30mph or more. It stuck the boat like a spear blowing a 12" hole in the bottom in about 3ft of water. He was lucky that the log kept the boat from sinking and it just sat there hanging on that log.
It took two of use and two other boats to go get that one for him. He never bought another boat after that.
 

Latest posts

Top