TI outboard mount

Thank you Greg,
I still have a few finishing touches to do, I am in the process of making a small plate that will mount on the arm that the motor mounts to.(that will give a bit more area for the motor to bolt up to.)
The backing plates for the gear track rails should be here tomorrow so I can finalize everything.
I will then take it out for the test. I feel very confident it is going to work great.
It is alot more solid than my previous mount, which was a piece of decking attached to my pvc rollbar.
I will give some feed back once testing is complete.

A few idle thoughts...
Could you extend the "middle" extrusion out to add extra support for the motor clamp, and then by adding a vertical connecting plate, you also solve the potential problem of the motor sliding outwards in heavy conditions..

Looks very professional!

_________________
Tony Stott
2012 Tandem Island "SIC EM" with Hobie spinnaker

Actually At least on Honda's and a couple other brands I have abused over the years the mount and locking screws appear to be designed to be used on a wooded transom board. The pointed spikes appear to be designed to sink into the wood to insure the motor doesn't slip. The motors vibrate quite a bit, and the wood obsorbs the vibration, whereas aluminum does not and would resinate and amplify the vibration noise into the hull (think base drum). If you still want to use aluminum and not wood, you can always glue rubber sheet on the mounting surface of the mount (would have the same effect).
Also don't under estimate the rotational force the prop at the bottom of the lower unit produces under power (way more than you would think).
If you do add a wood transom board make sure you use pressure treated wood (not soft pine 2x4 ), my first mount made from soft pine only lasted about a month in salt water.
Also always add a safety line to the motor so if it does fall off it doesn't go into davey jones locker (they don't float), I lost 5 or 6 small motors when I was younger hitting stumps on the mississippi. On a TI in the event of a violent capsize it's very likely the motor would slip off an aluminum mount (without rubber padding). Just speaking from experience here.
Hope this helps
FE

I used a motor on my TI for the first time this week. It's a design that I first saw while sailing with FE last summer with a few mods.

https://app.box.com/s/ndnn9pfcljz9jaa0x9y9qbqwfoikaadw

The mount rests on the gunwale with stabilization from the pieces inserted into the rod holders wrapped in 3M rubber splicing tape (those stabilizing pieces do not go to the bottom of the rod holder wells). The pressure treated wood is held down by the hooked fittings and a stainless hardware set that goes through the wood and the vertical mainsheet guide section. Note the Spectra safety lines that I hope will help keep the motor and support attached to the stern area.

https://app.box.com/s/liq51uekypa07q7qygvybuo0v4zjnu0a

Even on near-idle speeds, the little motor generated enough torque to rotate the prop forward/motor backward around the wood support by about 20 degrees of so. I was very surprised given that everything seemed very secure before I started. I'm now thinking of attaching a spectra line from the rear-most plastic cleat (or a substitute padeye) to the leg of the motor. Only thing I'm scratching my head on is exactly where - there is a warning about the leg being hot. B would clearly give more leverage and a more powerful retraining point.

https://app.box.com/s/gzv044v9g2vb8qhkwlwly7nw6xwy0xlt

Bob, I didnt know you had tried an aluminum mount.. You experience is much different than mine with the AL mount. The Suzuki also had the "point load" contact points on the back side mounting plate and I get a very secure mount with my AL setup. I have a lot of time on my setup now and Al works great for this application. The base drum analogy.. also way different than my experience. The Suziki 2.5 is water cooled and has a below the water line exhaust but because it sits very close to your head, its still loud - and its the outboard head itself that is loud - not some "hypothetical" vibration through the hull. I dont have the Honda but the newer ones are air cooled and are supposed to be a little louder than the water cooled Suzuki. A lot of people like the 2.3 Honda because its air cooled - no water pump to go bad or need a maintenance change every few years but the tradeoff is slightly louder. Sounds fall off with the cube of distance so its simply that if you sit near the outboard so that you can control it (outboard is in the rear, I sit in the rear also), your head is close to the engine and it will be loud. I always wear some noise ear protectors when motoring. My wife in the front seat just a few feet away doesn't think its too load at all (sound pressure falls of quickly with distance).

But.. definitely a good idea to have a safety. I have a line with quick clips on both ends that is attached to the mount. One end gets clipped to the part of my mount permanently attached to the hull, the other end gets clipped to the outboard. Quick clips on both ends because my mount is removable and the line and clips stay with the mount.

You also have to keep in mind for most people (FE always has his outboard down and running) is that you will also want to put the outboard up for sailing the boat (I dont even remotely want the drag of an outboard not running but still in the water). This ends up being a 30 pound weight balanced at the top of the mount and if you are out in some big wind and waves.. it needs to be robust. The mount needs to handle the torque from the prop when the outboard is down and running and also the force of the "pendulum" weight trying to swing around above the mount when the outboard is up.

One final thing that you also may need.. I am finding that about half the time I go out, I end up towing another TI or AI. A few days ago two of us both in TI's (four people) did a long down wind sail - many miles until the wind died. My outboard was up and out of the water for this sail. I then towed both of us back. At my mid throttle setting, we were making 5.7 mph (about 5 knts). This type of outing is of course not for everyone (some people dont even like to use the pedals LOL) but I really enjoy having this option. Sort of like using the lift at a ski resort.. There are some great sails at the lake Im on that require a shuttle.. but I dont need the shuttle (and the hassle of finding someone to drive the auto/trailer) - instead jus the the time for motoring. But then the next outing I go out on, no one has a motor and I remove both the outboard and the mount. Its nice not having any of the motor stuff back there most of the time.

Hi Walt,

No, I haven't tried an aluminum mount - this was my first day out with a motor on the TI. (Is it possible that you're referencing FE's posting?) I sailed about 20 miles out and back to my campsite and about half of that in open water in the Gulf. Slight wind chop, 2 - 3 foot seas, whitecaps on both port and starboard tacks. The motor was up almost the entire trip and I wanted to see what, if any, negative effects there were. I didn't notice any while sailing and was happy to see that the entire kit-and-kaboodle was still intact when I returned. The motor is on my port stern and on a starboard tack, rear of the port ama buried, and sitting up on the rear of the starboard haka (which was still out of the water) I think the mount kept the motor out of the water ('course, I do have to remember to move the handle out of the way..duh!).

I furled the sail, pulled the sideboard and rudder up and started the motor after returning to my launch area to see how it would work. I did get it to start, and after a few stalls I motored around the bay and then headed into a stream where the current was running 3 mph. My Lowrance was showing 5.0 mph at idle. Turning and heading back upstream required full throttle to reach that same 5 mph mark, but it did do it.

My post was to FE regarding needing rubber with AL to keep the outboard from slipping off and resonating like a drum also because of using AL. Both of these very much conflicted with my experience - so.. that is why I posted that. FE, I could not tell if you had actually tried AL or you were just speculating, sorry if I was incorrect in assuming you had actually tried an AL mount. I think different ways and materials to mount the outboard work fine, you can see a lot of different ways to do it in this thread and also others. And of course if your the inventive type building something like this, its also likely that you enjoy the process and will do something at least a little different than everyone else. All good!!!

Bobagain, are you a FL snowbird? Good that your setup works fine with the outboard in the up position (you probably already saw but your pictures didnt post). My outboard is on my starboard side and I can slightly tell I have the weight when sailing but its hardly noticeable. I have to watch the position of the handle so that I dont catch the sheet but it never catches anymore. My biggest balance issue was when I was loading the TI on the trailer and the outboard would try and tip the boat off one side (its a custom trailer). I just re-did the bunks - added new longer ones and moved the original ones out more so that it better supports the TI when Im loading. It still loads better without the outboard but overall not bad with the outboard.

Walt:
If aluminum works thats great, the Motors are likely designed to work with either wood or aluminum (I would think much more transom boards are aluminum these days (they used to all be wood yrs ago). As far as the resonating noise I was just speculating on that.

Just an FYI, I took a picture of the side of my mount that the outboard back side (with the tabs) pushes up against. You can see the marks on the AL from the outboard tabs (highlight with black arrows). They dont move at all. One other thing to note about this is that the height of the mount that contacts the outboard rear mounting plate is 4 and 7/8 inch. This picks up all the mounting tabs but the very bottom ones (vertical, the top ones are horizontal) probably could have used a little more top to bottom surface. However, I haven't had any issue at all with this and now have many hours and miles.



The picture below shows the safety clip - just in case for some reason the outboard came loose. I havent needed it so far but happy its there.



Picture below - my towing strap. I just added the bungee to handle shock loads that can happen when a boat goes by and creates a wake.

No - they post fine on mine. Do none of the three show up? Thanks for telling me!

FYI, I can see the pictures now, looks like a nice job! It also has the sheet line organizer similar to what FE suggested many posts back. I wouldn't think attaching the extra line anywhere on the shaft would be a problem at all from heat - or just put it where FE did - already tested. Another good thing about that extra line is that its no hassle when you rotate the outboard up, it just goes slack - tightens up when you put the outboard back down and that is when you need it.

Another cool feature about that spectra line supporting the motor is. For some reason at one time I wanted an automatic tilt up feature on my motors where I could tilt them up from the cockpit just by tugging on a line tied around the rear aka crossbar, then back to those spectra line via a hog ring. I had it on there for a while but found I never bothered with it so I got rid of it. Just like everything else on the boat, it has to be rock solid reliable, and whatever it is I have to use it often, if not it's removed from the boat (the boat is way too busy and compex, most people prefer the simplicity of the stock boat), I just personally can't get myself to be satisfied with 3mph average speeds in the normal light winds we have around here.
FE

I finally got to get out and test the motor mount, it works perfect. No twist, no added stress to the hull. I even towed the tandem to our launch point with the motor installed(50 miles) The motor didn't even think about moving.
This is a major improvement from the wood I had attached to my roll bar.

I finally got contented with my outboard mount. Thank you RPrince for sharing your idea.
Everyone with outboard for TI should look into this mount as it is really impressive.
RPrince mount has it all. It works as expected and the design was like professionally made.
Again, thank you RPrince. Now I can stop thinking about mounts and can now focus on enjoying my motor powered TI.

Never had any problem with mine. Still going strong, 2 seasons. Solid as a rock.
What I like about my placement is that it's out of my way and just right for reaching back and grabbing the throttle.
Can't think of a single thing I would change.

_________________
Mark
Tandem Island- 2013
2 - Sports - 2014