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Old 06 February 2008, 07:04   #1
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Country: UK - Scotland
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Fitting Auxilliary Engine to Zodiac 7-Man Pro

Hi

Has anyone ever fitted an auxilliary engine to a Zodiac 7-Man Pro? I'm desperate to fit a Tohatsu 3.5HP long-shaft in the spring, for piece of mind and reliability. I'm normally fishing with 2 other people on board in the Moray Firth or Atlantic (west coast) of Lewis, so there is little room for error if my main engine fails for any reason.

I do all the servicing myself - but I know engines can still fail.

I've only ever seen one other 7-man Pro with a Tohatsu 2.5HP auxilliary fitted, (pictured) but for the life of me I can't see how it works without somehow restricting the steering on the main engine. I've also attached another picture (not my boat) to give an indication of space. I reckon there is 10" of free space on the port side of my main engine at hard-lock. I have a navigation light pole on the starboard side.

Obviously it would need to be a custom bracket, as the transom has an angled section. The bracket would probably need to be hard against boat tube to allow clearance. I'm sure a blacksmith could make something up.

It's easy enough to remove the ski-tow hook too.

Any thoughts?
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Old 06 February 2008, 07:28   #2
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I'll start by saying I've no experience with your particular boat.It does look tight though.
There are a few older 2 stroke outboards out there that are nice and compact compared with that Tohatsu-this 2hp Evinrude (link to pic) is one. There's also these 2hp Yamahas (link) from the '70s which doesn't even have a recoil start-but is even narrower than the Evinrude above.

I wouldn't remove the transom eye-it'll be hard to tie down to the trailer otherwise!

Is the 40hp Yamaha any wider than the Tohatsu 40?
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Old 06 February 2008, 09:16   #3
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You would be suprised at how little space you need to fit an AUX.

see the picture below of my installation..
http://rib.net/forum/attachment.php?...4&d=1188600854

Things to bear in mind....

- When tilted forwards you have more space for the main engine to turn (I can turn mine on full lock with no chance of touching)

- With the AUX you dont really need it to be able to turn to full lock as you will find the easiest option is set the AUX straight and lock it in that position then use the main engine to steer.

- I do have to be a little careful when my main engine is down as well as the AUX as they will touch when I am steering sharp left.

- If you need to manouver in a tight space that is when you might use the AUX to steer, again you will be suprised at how much steerage you get even with a reduced lock.

- If you can, fit the AUX directly to the transom and not to a bracket as this makes the whole installation easier to use and less likely to break in heavy conditions. This will probaly mean you need to source a long shaft version of the motor. I tried a standard shaft on mine and it cavitated every time the boat went over even mild swell.

- the easy way to set the Aux up is hang it on the transom as far from the main engine as you can then test to see how it all goes together if you can afford to move the aux closer to the main engine to allow for more steerage on the AUX then go ahead.
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Old 06 February 2008, 19:06   #4
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Chris, dos your 4 hp aux work well for that size of Rib?
My rib is a 5.30mtr one, looking also for a aux, what about 2hp per mtr. of boat length.
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Old 06 February 2008, 19:12   #5
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Quote:
Originally Posted by Bertus View Post
Chris, dos your 4 hp aux work well for that size of Rib?
My rib is a 5.30mtr one, looking also for a aux, what about 2hp per mtr. of boat length.

2hp/metre is too much-with a 10hp mounted off centre your boat will feel off balance.

4-6hp will be fine. You only need to make displacement speeds.
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Old 07 February 2008, 02:04   #6
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Quote:
I wouldn't remove the transom eye-it'll be hard to tie down to the trailer otherwise!
Removing the transom eye should be okay. I tie down the boat in transit with a 1.5 tonne rachet strap across the boat between the console and the bench seat.

Quote:
Is the 40hp Yamaha any wider than the Tohatsu 40?
I measured the width of the Yamaha cowl - it's 14" wide, which I assume would be roughly the same as the Tohatsu 40HP.

The Tohatsu 3.5HP 2-stroke looks very slim. The short shaft is only 17kg. Think I read somewhere the long version is 22kg. Not sure of width though. Has 1.4 litre built in fuel tank giving a run time of approximately 45 minutes. Would be relatively easy to carry pre-mixed fuel (for top-up) in a 5 litre fuel tank.
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Old 07 February 2008, 02:11   #7
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Country: UK - Scotland
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Quote:
- If you can, fit the AUX directly to the transom and not to a bracket as this makes the whole installation easier to use and less likely to break in heavy conditions. This will probaly mean you need to source a long shaft version of the motor. I tried a standard shaft on mine and it cavitated every time the boat went over even mild swell.
The transom has an overhanging lip on it near the pontoons (I suspect for reinforcement) - so it will be impossible to fit directly here. Usining a transom bracket is the only way to fit.

I'm looking at long version auxilliary model only. The orginal Zodiac Pro's transom was designed for a short-shaft engine, however the newer models (like mine) need a long-shaft engine now.

Thanks for information - very helpful.
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Old 07 February 2008, 05:10   #8
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Quote:
Originally Posted by Bertus View Post
Chris, dos your 4 hp aux work well for that size of Rib?
My rib is a 5.30mtr one, looking also for a aux, what about 2hp per mtr. of boat length.
Bertus I get 4 knots or just over with mine so not blistering performance but it does what it needs to which is to give you steerage and / or get you away from danger if you ever break down in an awkward situation, so that you can attend to the main engine or put out a PAN PAN.
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Old 07 February 2008, 05:56   #9
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Quote:
Originally Posted by spartacus View Post
Removing the transom eye should be okay. I tie down the boat in transit with a 1.5 tonne rachet strap across the boat between the console and the bench seat.
That's not very good for the tubes. It overpressurises them.
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Old 07 February 2008, 08:43   #10
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Quote:
Originally Posted by Nos4r2 View Post
That's not very good for the tubes. It overpressurises them.
Agreed going to mark the tubes as the boat moves in transit.

I recon that Tohatsu is mounted on a bracket in the first photo but you have an odd shaped transom, probably have to have one made to fit. May be the way to go if you want to be able to steer as the engine could be further offset without cutting the tube to transom flange.

Pete
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