30 replies to this topic

[NBR]

IMHO it is not the weight of the motor on the transom but the torque transmitted to the transom from the lower unit when the motor is raised for transport and the road bounces the trailer and boat. Transom savers move the load from the transom to the trailer. I think repair to the trailer is prefered to repair on the transom.

[Fishing Rhino]

Well all that poses a question in my mind.  I checked the prices of transom savers and lock n haul, and they are comparable.  In fact, my transom saver with the compression spring costs more than the lock n haul.  Why does Nitro provide a transom saver rather than a lock n haul with their boats?

 

If I were in the boat business, on the scale of Tracker Marine/Nitro I'd be on top of every aspect of my product, and if there was something better for the same money, that's what I would provide with my product.

 

I'm still neutral, and would use either, but I wouldn't spend extra money to change what came with the boat.

 

And the first device to hold the lower unit up was a block of wood.  The lower unit was raised, and a piece of wood that had been trimmed to make a snug fit between the mounting bracket and the pivot on the lower unit of the outboard.  I can remember this from the 1950s as my best friend's father sold boats.  That was before Teleflex cable replaced the pulley systems.  Once the motor was tilted, it was then laid over on it's side, and secured so it could not flop around on the motor pivot.

 

That even preceeded power tilt and trim on outboards.  My friend's father sold Scott Atwater which was changed to Scott when McCulloch bought out Scott Atwater, and shortly after they renamed the outboard line McCulloch. 

 

I had one of these.  They were really junk.  The water pump was located at the top of the lower unit, and the exhaust would blow directly onto it.  What made it worse was that it would drain down and it ran dry until it picked up a prime.  There were two impellers.  One to cool the engine and the second for the "Bailamatic".  The bailamatic had a foot at the end of a hose that would be placed in the lowest point of the hull, usually at the stern.  It provided a constant suction at the foot which would suck up any water more than a quarter inch deep.

 

The Bailamatic impeller was kept cool, and lubricated by a hole in the plate between the two impellers that forced water into the Bailamatic chamber.

 

.

[Fishing Rhino]

I've been pondering the two methods of keeping the motor tilted while watching Pitmaster's Barbeque Competition.  Then it hit me.

 

The block of wood between the mouting bracket and the pivot housing works the same way as the Lock n Haul.  Granted it was a rather crude, low tech version, but the physics  is the same in the way the forces are distributed to the same two components of the engine, independent of the trailer.

[mc6524]

I came across a gentleman that made plastic inserts to replace the rubber grommets and it works great and now will last me indefinately.

[Long Mike]

Rhino, it's time to take your medicine.  You're rambling again.

[South FLA]

I use this: http://www.moto-stops.com/
I also use the clips to make sure engine doesn't move side to side.

I debated which was better and asked the opinions of a structural engineer from GA Tech and a mechanical engineer from Pratt and Whitney after asking which would be better years ago and they basically said the only way to relieve transom shock from trailering would be to remove the huge weighted lever (Engine) on the transom, which is not practical.

The original "transom saver" allows the weighted lever to rest against the trailer so the downward force is transferred to the trailer, for example as the trailer drops off a curb. The force is first transferred into the tires, shocks/torsion axle, and then finally anything attached to the trailer in the opposite direction as the trailer levels out while being pullled along. The important aspect here is that the same weighted lever which is supported by the trailer through the transom saver also has forces acting in the opposite direction and ultimately back unto the transom. So unless you can come up with a device that cushions and distributes forces from rough trailering in BOTH directions you won't be protecting your transom completely! The moto stop or devices similar to it cushion/disperse impact force on transom to an extent on the drop, but when leveling out they provide no protection in the opposite way, the force is applied to transom. Therefore no solution is ideal, but you can avoid rough roads or at least avoid driving too fast down rough roads. I went with the moto_stop because of ease of use and the fact that if the transom saver if by SLIM chance becomes detached from the trailer or lower unit on a harsh bounce then you could have a severe situation. Imagine the arm which you have secured to the trailer coming off and pole vaulting into the road at speeds while still being attached to your lower unit, OUCH!

Recommended Yamaha Trailering Support Option:

https://www.yamaha-m...5/0/detail.aspx

Mercury Recommendation:

http://www.mercuryma...aqs/#Trailering

Evinrude Etecs having built in trailering brackets!

Another interesting article:

http://www.boatus.co...ansomsavers.asp

[Traveler2586]

START QUOTE: "What precautions should I take when trailering my outboard powered boat with the engine attached?" [ I believe they are refering to the smaller motors ]

"Trailer your boat with the outboard tilted down (vertical operating position). Shift the outboard to forward gear. This prevents the propeller from spinning freely. If additional ground clearance is required, the outboard should be tilted up using an accessory outboard support device. Refer to your local dealer for recommendations. Additional clearance may be required for railroad crossings, driveways and trailer bouncing.

IMPORTANT: Do not rely on the power trim/tilt system or tilt support lever to maintain proper ground clearance for trailering. The outboard tilt support lever is not intended to support the outboard for trailering."  END QUOTE:

 

 

Years ago I came across a video on an engineering website that was done under contract to a saltwater boat manufacture. The purpose of the slow motion study was to gain an understanding of the impacts the new larger engines have on transoms, on the water (load forces) and off the water (free forces); the results of the study were to be used in new craft transom design.

 

The engineering firm placed sensors at key points on the transom mount (I think it was two at top and two at the bottom of the mount between the mount and the transom) to study the toque of the motor while pushing a boat, and while being towed. They simulated road bounce by hydraulics that was not shown in the video; and did both on the water & on the road studies that were not filmed (or shown).

 

As I’ve said it’s been years since I saw this video, but the main point that I recall was that small, sharp, vibrations were not a “big” problem for the motor or the transom, the big problem is the free load toque of the motor on the mounts when towed on roads that undulated the trailer up & down quickly. Some of the energy of the undulations was absorbed by the trailer tires and trailer springs, the rest was fed to the trailer, boat and motor.
With the motor tilted forward, and unbalanced, the undulations created a rocking force, top-to-bottom, at the top motor pivot point and transom; this translated into a rocking force that was translated via the hydraulic lifts to the lower half of the motor mount and into the lower transom. This free force action was deemed different from the load force imparted on the transom while “wave skipping”.

 

In the conclusions of the video the engineer stated that a support (transom-saver) firmly mounted to the trailer frame and under support pressure of the lower unit was recommended for transport to prevent the free load rocking force; the support would divide the load of the motor between the transom and the trailer.

Recalling the above, I now question my new spring loaded transom saver that rests on a trailer roller which has a 5/8” mounting shaft; that doesn’t strike me as a solid support.

 

[South FLA]

START QUOTE: "What precautions should I take when trailering my outboard powered boat with the engine attached?" [ I believe they are refering to the smaller motors ]

"Trailer your boat with the outboard tilted down (vertical operating position). Shift the outboard to forward gear. This prevents the propeller from spinning freely. If additional ground clearance is required, the outboard should be tilted up using an accessory outboard support device. Refer to your local dealer for recommendations. Additional clearance may be required for railroad crossings, driveways and trailer bouncing.

IMPORTANT: Do not rely on the power trim/tilt system or tilt support lever to maintain proper ground clearance for trailering. The outboard tilt support lever is not intended to support the outboard for trailering."  END QUOTE:

 

 

Years ago I came across a video on an engineering website that was done under contract to a saltwater boat manufacture. The purpose of the slow motion study was to gain an understanding of the impacts the new larger engines have on transoms, on the water (load forces) and off the water (free forces); the results of the study were to be used in new craft transom design.

 

The engineering firm placed sensors at key points on the transom mount (I think it was two at top and two at the bottom of the mount between the mount and the transom) to study the toque of the motor while pushing a boat, and while being towed. They simulated road bounce by hydraulics that was not shown in the video; and did both on the water & on the road studies that were not filmed (or shown).

 

As I’ve said it’s been years since I saw this video, but the main point that I recall was that small, sharp, vibrations were not a “big” problem for the motor or the transom, the big problem is the free load toque of the motor on the mounts when towed on roads that undulated the trailer up & down quickly. Some of the energy of the undulations was absorbed by the trailer tires and trailer springs, the rest was fed to the trailer, boat and motor.
With the motor tilted forward, and unbalanced, the undulations created a rocking force, top-to-bottom, at the top motor pivot point and transom; this translated into a rocking force that was translated via the hydraulic lifts to the lower half of the motor mount and into the lower transom. This free force action was deemed different from the load force imparted on the transom while “wave skipping”.

 

In the conclusions of the video the engineer stated that a support (transom-saver) firmly mounted to the trailer frame and under support pressure of the lower unit was recommended for transport to prevent the free load rocking force; the support would divide the load of the motor between the transom and the trailer.

Recalling the above, I now question my new spring loaded transom saver that rests on a trailer roller which has a 5/8” mounting shaft; that doesn’t strike me as a solid support.

 

 

So basically if the boat is securedly anchored to the trailer (tie downs
straps for the bow and stern) and using a solid support from trailer to the
lower unit , you can reduce the rocking force on transom,  but with a
spring loaded transom saver you are only allow the rocking to happen,
correct?
 

[Traveler2586]

"So basically if the boat is securely anchored to the trailer (tie downs
straps for the bow and stern) and using a solid support from trailer to the
lower unit , you can reduce the rocking force on transom, but with a
spring loaded transom saver you are only allow the rocking to happen,
correct?"

 

IMHO, one would think so, so I'm starting to question the use of one in my mind. But let me say I'm am not a mechanical engineer.

 

Here's a case in point on the forces involved. Last year I was on my way down to Lake Guntersville, AL. I would do a walk-around of my rig at each rest/fuel stop which included checking the boat tie downs and the transom saver to insure everything was snug. While going through Knoxville, TN. I went on a section of elevated roadway that was very uneven; it created undulations in my rig that felt like I was riding a bucking bronco. Next thing I know a motorist pulls alongside and indicates I have a problem with my trailer, so I pull over to find my transom saver had come off the roller, drug on the roads surface, and broken the lower tang of the fork. That means the lower unit traveled at least three inches for the fork to clear the roller. This could only be a result of the motor rocking and lifting the transom saver off of the roller.
 

So now I use a safety strap on the transom saver that runs from one side of the fork around the frame member to the other side of the fork; hopefully that will prevent a similar incident in the future. The problem is, it’s a pain in the arse to put on while the boats live wells are draining.

 

 

Bottom line…. IMHO, I don’t think any of the devices currently on the market can prevent motor rocking, they may dampen it to some extent but not eliminate it, there’s just too much weight in the power head, and the rubber lower unit safety strap on a transom saver will give way - it’s only designed to keep the saver attached to the lower unit; and the wedge devices transfer the full force of the rocking into the transom rather than dividing the motors weight between the transom and the trailers frame.

 

Edit to add pic

 

 

[Glenn]

I use the standard transom saver.  Been doing it for 25+ years now without any issues, so why change?

 

That said, be sure to remove it when launching the boat - especially if you strap it on the lower unit with a bungee cord.  The resulting impact with the prop during the hole shot launches the transom saver way, way, WAY up into the air, and it instantly sinks upon crashing into the water seemingly minutes later!

 

Don't ask me how I know this. 

[Fishing Rhino]

I use the standard transom saver.  Been doing it for 25+ years now without any issues, so why change?

 

That said, be sure to remove it when launching the boat - especially if you strap it on the lower unit with a bungee cord.  The resulting impact with the prop during the hole shot launches the transom saver way, way, WAY up into the air, and it instantly sinks upon crashing into the water seemingly minutes later!

 

Don't ask me how I know this. 

 

 

Do you think that could be replicated so that you could take a video? Sounds like it would make for great entertainment. I'll bet Bill Dance might do it if you give him the idea. He loves his bloopers, and so do I.

[Fishing Rhino]

"So basically if the boat is securely anchored to the trailer (tie downs
straps for the bow and stern) and using a solid support from trailer to the
lower unit , you can reduce the rocking force on transom, but with a
spring loaded transom saver you are only allow the rocking to happen,
correct?"

 

IMHO, one would think so, so I'm starting to question the use of one in my mind. But let me say I'm am not a mechanical engineer.

 

Here's a case in point on the forces involved. Last year I was on my way down to Lake Guntersville, AL. I would do a walk-around of my rig at each rest/fuel stop which included checking the boat tie downs and the transom saver to insure everything was snug. While going through Knoxville, TN. I went on a section of elevated roadway that was very uneven; it created undulations in my rig that felt like I was riding a bucking bronco. Next thing I know a motorist pulls alongside and indicates I have a problem with my trailer, so I pull over to find my transom saver had come off the roller, drug on the roads surface, and broken the lower tang of the fork. That means the lower unit traveled at least three inches for the fork to clear the roller. This could only be a result of the motor rocking and lifting the transom saver off of the roller.
 

So now I use a safety strap on the transom saver that runs from one side of the fork around the frame member to the other side of the fork; hopefully that will prevent a similar incident in the future. The problem is, it’s a pain in the arse to put on while the boats live wells are draining.

 

Bottom line…. IMHO, I don’t think any of the devices currently on the market can prevent motor rocking, they may dampen it to some extent but not eliminate it, there’s just too much weight in the power head, and the rubber lower unit safety strap on a transom saver will give way - it’s only designed to keep the saver attached to the lower unit; and the wedge devices transfer the full force of the rocking into the transom rather than dividing the motors weight between the transom and the trailers frame.

 

 

 

I'm wondering which came first, the chicken or the egg.

 

Did the fork break which allowed the saver to drop, or did the saver bounce free and then drop which caused the saver's fork to break?  The hammering you've described might have broken the fork.  Just a thought.

[Traveler2586]

I'm wondering which came first, the chicken or the egg.

 

Did the fork break which allowed the saver to drop, or did the saver bounce free and then drop which caused the saver's fork to break?  The hammering you've described might have broken the fork.  Just a thought.

There was no damage to the roller or the roller shaft so I would think the upward movement of the lower unit pulled the TS off the roller; and it was the lower tang on the fork that broke, I suspect from digging into the roadway.  But I don't positively know.

[Fishing Rhino]

As I understand it, the motor should not tilt up or down if it is equipped with hydraulic tilt and trim.  The older outboards had a mechanism on the pivot bracket which "grabbed the tilt pin when the engine was shifted into reverse.  That prevented the motor from tilting up when in reverse.

 

I've looked at my boat and motor.  There is no such device.  Even if there were, there would be no tilt pin for it to "grab".   The motor must be held in place by the hydraulic piston so that it will not tilt up when reverse is used.  If the motor can rock enough to drop the fork from the trailer, there has to be some problem in the hydraulic system, be it a seal, valving, etc.

 

Note the angle of the transom saver in this photo.

 

 

Mine is even closer to horizontal.  There is no way that can put significant upward thrust on the motor.  When the trailer encounters a bump in the road, the boat and trailer are compressed together.  That would put no force into the transom saver, unless you want to count the possible tiny bit of compression of the carpet on the bunks.  Now, when you run over a pothole, the boat will tend to separate from the trailer.  When that happens, the transom saver if secured at both ends, would try to draw the lower unit down.  But since there is not solid connection between the saver fork, and the trailer roller, all that happens is that the fork separates a bit from the trailer roller.

 

When the boat drops back onto the trailer, that gap between the roller and the saver fork closes, and the downward thump is absorbed by the transom, not the saver. 

[Long Mike]

When I install my transom saver at the end of the day I trim the motor down FIRMLY into it.  I've had no problems with the motor bouncing as I travel.