Fixing outboard motor to dinghy floor for roof rack

Submitted: Thursday, Nov 21, 2013 at 08:58
ThreadID: 105207 Views:3634 Replies:4 FollowUps:11
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Gday folks. I'm trying to work out a simple way to fix my 15hp outboard to the floor of my dinghy so I can winch them together on to the roof. Obviously space and ease of use is a factor. Any suggestions and/or photos would be a big help as I'm struggling to find any examples on the net. Cheers
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Reply By: Herbal - Thursday, Nov 21, 2013 at 10:25

Thursday, Nov 21, 2013 at 10:25
Might need a bit more information to give a direct answer...But if it's of any use I can think of some suggestions.

Is it 4 or 2 stroke? If it is 4 then you will be limited to just how far you can tilt it (or lay it flat). If it is 2 stroke you only have to worry about the gear oil when laying it flat.

15 is quite large to be taking off and putting on every time you want to use it. It might be worth looking at a small 2 stroke... I have a 2.2 Suzuki which you can pick up in one hand. It pushes a 12 foot tinnie along with 2 people on board quite well. I bought it new and I think it was about $780.

A 15 plus the boat might be over your roof rack weight limit. If the motor is fixed to the floor then inverted, you will have the weight of the motor "bouncing" in that one spot on the hull...I just had a look, my 6hp short shaft Mercury weighs 31.1kg. The Suzie is in a corner so I can't get to it to see what it weighs. So let's assume your 15 weighs about 50 to 60kg, that is a lot of weight to put in one spot on the hull. You might want to get a boat builder or engineer to look at it and give an opinion.

I assume you are towing something...A trailer or caravan. Maybe you could rig a bracket or maybe even just a trolley, and carry the motor on or in your trailer/van.
AnswerID: 521817

Follow Up By: Brian 01 - Thursday, Nov 21, 2013 at 10:44

Thursday, Nov 21, 2013 at 10:44
I have to agree with Herbal regarding the weight limitations.
You are roughly doubling the weight on the rack, which may or may not be OK depending on your vehicle and roof rack combination.
Then comes the problem of getting the lot up there, It will require a large effort on a manual winch type loader such as the Rhino rear one, the Rhino electric will not handle it as you will surely strip the quite weak worm gear assembly, and from what I have seen of side loaders, all of them would collapse before the boat was on the roof.
Then you have the concern of all that weight suspended from the hull and what happens if it comes adrift in transit.
My personal advice would be to put it somewhere else.
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Follow Up By: Jagger - Thursday, Nov 21, 2013 at 11:58

Thursday, Nov 21, 2013 at 11:58
Yep understand your concerns so just exploring my options and the possibilities. I've got a 2 stroke 15hp yammy weight 38kg and dinghy at 80kg so total of about 118kg. The roof rack is rated to 200kg and I have a 1500kg remote operated winch located on bull bar with dyneema with latch to rear of landcruiser. It goes up over rear mounted rollers......a breeze with dinghy alone and will test both in next few days under temp arrangement. I thought there might be some existing system around or something cheers
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Reply By: Jagger - Thursday, Nov 21, 2013 at 11:36

Thursday, Nov 21, 2013 at 11:36
Yep understand your concerns so just exploring my options and the possibilities. I've got a 2 stroke 15hp yammy weight 38kg and dinghy at 80kg so total of about 118kg. The roof rack is rated to 200kg and I have a 1500kg remote operated winch located on bull bar with dyneema with latch to rear of landcruiser. It goes up over rear mounted rollers......a breeze with dinghy alone and will test both in next few days under temp arrangement. I thought there might be some existing system around or something cheers
AnswerID: 521820

Reply By: Member - bungarra (WA) - Thursday, Nov 21, 2013 at 16:09

Thursday, Nov 21, 2013 at 16:09
All of what has been said makes a lot of sense.

I have my outboard (15hp 2 stroke mercury ...similar weight to yours) ) on the back of the caravan.....the boat is on a Custom Boat Loader and there is sufficient weight capacity ( on the roof as well as the floor of the loader) for me to do something along the lines of what you have suggested if I wasn't towing the 'van...so I am interested in the replies and solutions

Have you thought about strapping the motor to the dingy as you intended.....but once it is up on the roof then somehow dropping the motor onto the roof rack floor?

This way the motor is winched up easily as per your original post but during travel the motor is resting/supported on the roof rack base.....thus eliminating the stress on the dingy

bit tricky the mechanism to lower the motor off then back to the boat for loading/unloading...but a bit of thought could get around it perhaps?..a cradle / sling of some sort that is easily lowered the short distance down / up

just thinking outside the aquare a little
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AnswerID: 521832

Follow Up By: Jagger - Thursday, Nov 21, 2013 at 16:33

Thursday, Nov 21, 2013 at 16:33
Yeah good idea.just how to that's all. I could winch up the motor separately but how would you do that without hitting the vehicle because there's no leverage or nothing to slide up
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Follow Up By: Member - bungarra (WA) - Thursday, Nov 21, 2013 at 16:50

Thursday, Nov 21, 2013 at 16:50
Definitely need the motor contained inside the dingy for on/off

if the motor was strapped to a board/plank/...(timber or Ali.) that was slung across two seats with the motor hanging down inside {towards the floor of the dingy} for protection/clearance then with a bit of thought the plank to which it is strapped / bolted could then be lowered onto the roof rack floor...

this way the plank is flat on the roof rack floor and the motor remains strapped to that....still insitu in relation to the dingy....but supported by the roof rack floor not the dingy

....maybe even the motor inside a purpose built box....protected and maybe easier to strap down.......doesn't have to be too fancy how it is attached to the boat....its going up and down to the roof, not travelling anywhere

Easier said than done but feasible with a bit of brainstorming.....I haven't really stopped to give it deep thought....just off the cuff quick idea that's all
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Follow Up By: Jagger - Thursday, Nov 21, 2013 at 17:50

Thursday, Nov 21, 2013 at 17:50
it got the better of me so I had a test run over past hour. The motor has a cowling cover plus full cover so I lowered the winch latch down the side of the landcruiser down the rear door as a ramp sort of thing. When the motor got as far as I could get it I climbed on the rack and lifted the motor only slightly to unlatch then lifted on to the rack. Did the same in reverse. Easy!! Dyneema rated to 3tonne and winch on bull bar to 1500kg and latch to 3T so I reckon it wont fall.....only me right. Unless I think of something better I can actually rely on doing everything myself and not rely on my 8 year old son or wife. I like your idea of strapping to a box or plank but its how I unlatch or lift and latch it again is the hard one.
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Follow Up By: Brian 01 - Thursday, Nov 21, 2013 at 19:04

Thursday, Nov 21, 2013 at 19:04
I suggest that you remove something of similar bulk but lighter from inside the vehicle to make room for the motor in there, then put the lighter item/s on the roof.
Much easier to get both on and off, less chance of injuring yourself - a sore back can severely hamper your holiday, less chance of a heavy missile coming off the roof in an accident.
Provided you rigidly secure the motor in the vehicle, it will be safer in there.
Unless you have a portable trailer, I'm not keen on the practice of mounting an outboard anywhere on a van as you then have to relocate it to the car when putting the boat in the water. No point doing the job twice, or four times if you also count the return journey.
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Follow Up By: Jagger - Thursday, Nov 21, 2013 at 21:44

Thursday, Nov 21, 2013 at 21:44
the wife might be a bit sour on the motor in the car but I have to say what choice have we got. I agree about the lighter stuff on the roof rack though. maybe I can make that work somehow
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Follow Up By: gbc - Friday, Nov 22, 2013 at 06:23

Friday, Nov 22, 2013 at 06:23
http://www.exploroz.com/Vehicle/Boats/Roof_Toppers.aspx

There's a shot of a tinny with an ally frame in it for the outboard.

Note, it's not only 4 strokes which need to be stored a certain way, your 2 stroke manual will show the correct way to lay it down (usually on it's back with the mounts in the air) so the water drains properly.

Your idea is sound, and has been done before. Just needs the correct mount inside the boat, and the correct orientation for the motor when in the travel position.
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FollowupID: 802747

Reply By: Member - Beatit (QLD) - Friday, Nov 22, 2013 at 19:43

Friday, Nov 22, 2013 at 19:43
How about something like this.

AnswerID: 521928

Follow Up By: Jagger - Friday, Nov 22, 2013 at 19:50

Friday, Nov 22, 2013 at 19:50
now your talking....how do I get one of those or is there a plan. I think Ive seen this somewhere or it may well be yours before but need to know how to fix it to floor of dinghy and what system to latch and unlatch it? that would be a great big help. 15hp new Yamaha to s 3.75M seajay angler . I can get one engineered in WA if none available already before xmas when I take off. cheers
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Follow Up By: Member - Beatit (QLD) - Friday, Nov 22, 2013 at 20:09

Friday, Nov 22, 2013 at 20:09
Have a close look at this photo, it shows tabs welded to the tinnie frame to which the crate is bolted.


This what the frame looks like, I had made by the guy that made my loader.
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Follow Up By: Member - Beatit (QLD) - Friday, Nov 22, 2013 at 20:11

Friday, Nov 22, 2013 at 20:11
PS>
You can see in the O/B crate shot that the motor sits on its normal transom mounts in the crate. I load it lying down so that the O/B hangs on the mounting timber, this allows me to use the carry handle on the O/B. I then slide the skeg into the slotted timber on the bottom and then lift the crate in a vertical position. At this stage I fit a bolt through the transom mount, this a wingnut for convenience ( can see this in the photo). I also fit a piece of aluminium that has holes cut out to fit the lugs on the outboard (the ones on which it rests if placed on the ground with the carry handle facing up) – this is bolted to the frame and prevents the motor from twisting whilst in the crate. This is a critical piece that is about 5mm thick.

The crate is bolted into the boat by way of 4 bolts and 4 tabs welded to the tinnie frame.

The guy that made the rack welded the crate for me, I did the retaining bits. He is also a marine engineer and advised me to make sure that the motor is dry when loading because water can run into the cylinder head if the motor is inverted like I do.
We have done a rugged 3 months on some inhospitable roads and this system has stood up well. Nothing cracked, shook loose or broke on this trip and I found it to be 100% reliable.
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