Merc 44 transom height & Extension

[Yellowjacket]

I'm working on setting up my transom for a DSR (used to be a DMR) and need some help.

First of all, I know the prop shaft center line limit of 3/4 of an inch below the bottom as the highest setting I can have, but how low should I be able to set it? Or, to put it another way how much might I need to drop it below the 3/4 of an inch position?

Also is the tower height of a 44xs the same as 35ss? If not, does anybody know how much the difference is. I have a 35ss tower now but will eventually upgrade to the 44xs..

Finally, if I want to run in DmR how much higher would you run than in DSR?

What I'm trying to figure out is how much variation I need in transom height from the lowest setting (stock setup rough water) to the highest (no height limit in mod) and try not to have to do any more than shim it.

Any insight would be most helpful.

[ZUL8TR]

transom

I do not have a 44 to answer this but there must be somebody out there who does to give up this info?

[madstork]

Yellowjacket,

My 44XS tower 13" from the top of the steering bar plate to the prop shaft.

Sincerely,

Doug Follett
87-P

[pearson95m]

I'm working on setting up my transom for a DSR (used to be a DMR) and need some help.

First of all, I know the prop shaft center line limit of 3/4 of an inch below the bottom as the highest setting I can have, but how low should I be able to set it? Or, to put it another way how much might I need to drop it below the 3/4 of an inch position?

Also is the tower height of a 44xs the same as 35ss? If not, does anybody know how much the difference is. I have a 35ss tower now but will eventually upgrade to the 44xs..

Finally, if I want to run in DmR how much higher would you run than in DSR?

What I'm trying to figure out is how much variation I need in transom height from the lowest setting (stock setup rough water) to the highest (no height limit in mod) and try not to have to do any more than shim it.

Any insight would be most helpful.

I’ll try and help ya on this one.

I run my DSR anywhere between 3/4” and 1 1/8” (3/8” variation) depending on water conditions. However My shim sticks vary by as much as 1” due to kick out (angle of motor). For example: ½” shim stick on my boat with 1/8” kick OUT puts me right at ¾” height. However, if I kick my motor UNDER 1/8”, I’m closer to the 1 1/8” height.

DMR’s vary because the tower housings vary. I can’t run my stock 44xs motor on my Mod boat without an adapter plate to raise the transom. My mod motor tower is a bit shorter than my stock 44xs. And from what I understand, these tower housing vary from mod motor to mod motor. Why they don’t just make them all the same is beyond me… However, with that said its pretty darn close. I only need about another ½” of transom to get my 44xs to fit without an adapter plate.

The height you would run your mod motor can vary also. I’ve heard of people running them level 0”. I personally run mine at ¾” (same as my stock 44xs). The biggest deciding factor for this height (as I understand it) is the gear foot you use. I use the stock 44xs gear foot on my mod motor. However, other gear foots sometimes require different elevations for the best results.

I don’t know anything about the 35ss tower… sorry can’t help there

If I were you and had a fresh transom to start with… I’d set my mod motor up for ¾” with 1/8” kick UNDER… and cut my transom for that. For me, I don’t think I’d ever go lower than that, nor would I kick under more than that with my mod. Then I’d put my stock 44xs on the boat and hope it worked. If not, cut another ½” off the transom and have a transom jack built.

[jeff55v]

I have never run my DSR below 7/8". I usually stay near the 3/4" limit.

[Yellowjacket]

Thanks for all the help guys, I think that tells me most of what I need to know. I'll compare the info from Doug with my 35ss tower and that should get me in the ball park.

I'm going to have to raise the transom a good 3 inches or a bit more to get where I need to be. That's going to but the clamps right on the line where I am adding height to the transom (or a bit higher) so I will likely come up with a metal sandwich plate or angle brackets (like some folks recommended for the other transom mod thread a couple of months back) to make sure I don't have any structural issues.

Again thanks for the help.

[Yellowjacket]

I had a CAD model of my lower unit and the boat, and to get it right before I started cutting wood I did a quick model of the clamps and then oriented them correctly with respect to the end of the prop shaft.

Here is a side view of the boat and motor lower unit and clamps. What surprised me a good bit was how much the height changes with changes in kickout. The angle from the pivot to the end of the shaft is actually 43 degrees, which means the shaft moves out as much as it moves down when you are adjusting propshaft angle.

What I'm probably going to do is set it up with the propshaft being level at a depth of one inch (as shown), which means I will have a range of adjustment with the shaft level, and if I kick it in a bit I should'nt need more than a half an inch of shims under the saddle. If you measure from the bottom this transom would be at 13.75 inches.

This gives a 1 inch deep running height with no kick out, and with a .25 inch shim the motor will be at .75 inches with the motor level. This should let me run as much as 1/8 of an inch of kick out with no shims, With the motor kicked in I shoudn't need more than a half to 3/4 of an inch of shims under the saddle and still be up at the legal limit for a stock class boat.

I was also pleased that the reach isn't that much to get to where the clamps are, the total buildup is about 3.5 inches, which shouldn't be too bad.

[pearson95m]

Exactly! I like the work. Now, can i get a copy of the CAD layout? I've been putting together some plans for a new boat in Cad and would love to add this information to it.

[Yellowjacket]

Exactly! I like the work. Now, can i get a copy of the CAD layout? I've been putting together some plans for a new boat in Cad and would love to add this information to it.

Josh,

What CAD sysem are you using? The models are in Solid Edge, but I can transform them to IGES or Step files, they aren't very large, I can probably just email them to you.

What I did with the model was create a coordinate system to import the motor part models (clamp and gearfoot) to the assembly. You would have to import them and locate them in your model. In 20/20 hindsight I should have centered an assembly at the rocking point and I could have much more easily rocked the gearfoot about the pivot point. I can still do that but haven't bothered.

The gearfoot is a 35ss/55h, the outside shape is a close as I could model it measuring it with mic's, there isn't any detail to the insides, it's just a lump. The brackets aren't very detailed, just a close approximation, but the are fine for this purpose.

[lngnckboatworks]

cad

I had a CAD model of my lower unit and the boat, and to get it right before I started cutting wood I did a quick model of the clamps and then oriented them correctly with respect to the end of the prop shaft.

Here is a side view of the boat and motor lower unit and clamps. What surprised me a good bit was how much the height changes with changes in kickout. The angle from the pivot to the end of the shaft is actually 43 degrees, which means the shaft moves out as much as it moves down when you are adjusting propshaft angle.

What I'm probably going to do is set it up with the propshaft being level at a depth of one inch (as shown), which means I will have a range of adjustment with the shaft level, and if I kick it in a bit I should'nt need more than a half an inch of shims under the saddle. If you measure from the bottom this transom would be at 13.75 inches.

This gives a 1 inch deep running height with no kick out, and with a .25 inch shim the motor will be at .75 inches with the motor level. This should let me run as much as 1/8 of an inch of kick out with no shims, With the motor kicked in I shoudn't need more than a half to 3/4 of an inch of shims under the saddle and still be up at the legal limit for a stock class boat.

I was also pleased that the reach isn't that much to get to where the clamps are, the total buildup is about 3.5 inches, which shouldn't be too bad.

what program do you have
there ???

[Yellowjacket]

what program do you have
there ???

I have Solid Edge, it's a pretty good program. At work I'm designing turbine engines with it and it can do anything that we need to do with it.

I also have an old version "Inventor", it is very similar in how you model stuff and create surfaces. These are pretty much "good" CAD programs, not the best, but really, they are as good as you need for designing most anything. Top shelf programs (like Catia or Unigraphics) are much more expensive and really not much more useful for a single designer. The top shelf programs are better if you have 20 designers and are interfacing and working on big programs, but really the top reasonable cost programs (if $5k for a seat and $1500/year in maintenance is "reasonable") can do most anything that you need to do. The skill of the person doing the work is more of a factor than the program. Most of the programs work pretty much the same way, but they each have things they do better or a bit differently.

[lngnckboatworks]

I have Solid Edge, it's a pretty good program. At work I'm designing turbine engines with it and it can do anything that we need to do with it.

I also have an old version "Inventor", it is very similar in how you model stuff and create surfaces. These are pretty much "good" CAD programs, not the best, but really, they are as good as you need for designing most anything. Top shelf programs (like Catia or Unigraphics) are much more expensive and really not much more useful for a single designer. The top shelf programs are better if you have 20 designers and are interfacing and working on big programs, but really the top reasonable cost programs (if $5k for a seat and $1500/year in maintenance is "reasonable") can do most anything that you need to do. The skill of the person doing the work is more of a factor than the program. Most of the programs work pretty much the same way, but they each have things they do better or a bit differently.

thanks, i have inventor, ill check out solid edge