Fitting Auxilliary Engine to Zodiac 7-Man Pro

spartacus · 06 February 2008, 12:04

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?

Nos4r2 · 06 February 2008, 12:28

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?

Chris · 06 February 2008, 14:16

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.

Bertus · 07 February 2008, 00:06

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.

Nos4r2 · 07 February 2008, 00:12

Quote:

Originally Posted by Bertus

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.

spartacus · 07 February 2008, 07:04

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.

spartacus · 07 February 2008, 07:11

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.

Chris · 07 February 2008, 10:10

Quote:

Originally Posted by Bertus

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.

Nos4r2 · 07 February 2008, 10:56

Quote:

Originally Posted by spartacus

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.

Pete7 · 07 February 2008, 13:43

Quote:

Originally Posted by Nos4r2

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

Nos4r2 · 07 February 2008, 13:55

Quote:

Originally Posted by Pete7

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.

Looking at the 1st pic again I think you're right.I think you're probably right about having one made to fit too-the pad doesn't look like any standard aux bracket pad I've seen.That may well be what's been done.

PacificNWrib · 07 February 2008, 16:23

I am glad someone else is working on this situation. I am in the middle of doing that same setup on mine. I have a 50HP Mariner and a 4HP Mariner on the way. I found this bracket and I think it is possible to make it narrower if the need arises.

I fish a lot with two or three in my RIB. And having a reliable backup/trolling motor just makes sense.

I will post some photos of the process. I need to do some transom work before I mount the engines.

If you google Garelick, they have a fixed mount for an auxilary outboard.

http://www.garelick.com/product.php?pnumber=71078#

mike-stgt · 07 February 2008, 21:24

Hi, i also have an older Pro 7 with a 40HP Mariner ( Yamaha 2cyl).
I tried to fix a 4hp Mercury, but ther wasn`t enough space for that little engine. The solution will be to fix a bracket to the hull and store the auxillary
engine inside. In case of trouble, you will run the engine in a blocked straght position and control the direction by the main engine with the normal steering.

Greetings from Stuttgart/ Germany
Mike

spartacus · 07 February 2008, 22:14

Quote:

That's not very good for the tubes. It overpressurises them.

Although the webbing strap goes over the boat, it is not over-tightened. I also used padding so the strap is not in direct contact with the tubes. No marks are left - and the tubes are only pressurised prior to launching.

Worst case scenario - I could fit a bracket on the transom and store the auxilliary on-board, however this isn't ideal, especially in in moderate sea.

spartacus · 07 February 2008, 22:18

Quote:

Hi, i also have an older Pro 7 with a 40HP Mariner ( Yamaha 2cyl).
I tried to fix a 4hp Mercury, but ther wasn`t enough space for that little engine. The solution will be to fix a bracket to the hull and store the auxillary
engine inside. In case of trouble, you will run the engine in a blocked straght position and control the direction by the main engine with the normal steering.

Greetings from Stuttgart/ Germany
Mike

Thank you Mike - do you have pictures? I know the Pro (Mk 1) has a different transom set-up, but I'd be interested to see all the same.

Thank you.

mike-stgt · 08 February 2008, 20:38

Hi there.
The transom is a little different in design , but not in size.

Here is my Zodiac.
Mike

ian parkes · 08 February 2008, 23:39

My boat should have a long shaft , however i have just bought a 3.5 tohatsu and Iam hoping that hinged mountiong bracket will overcome the problem .

The simple brackets have the most movement 370mm . The idea is that tohatsu will stay in the down position and the bracket will lift it clear of the water .
Ill know for sure when the bracket arrives , if not its back to plan 1 of removing the motor when not in use .

the guy i bought the tohatsu from used it on a shetland cruiser and said it pushed that ok even against soem tide tide tamar estuary so hopefully it will do the job because there is no way a bigger motor will fit .

spartacus · 14 March 2008, 00:51

Just taken delivery of my Tohatsu 3.5hp, 2-stroke, long-shaft auxilliary engine. Weighs 17kg. 4-stroke wasn't much more in terms of cost but it weighs more, is 4" wider and is likely to be more expensive to service. As space is of a premium - it was a no brainer.

The garage never stays tidy during the winter - kids eh!

I'm still investigating options for fitting it. The transom bracket (pictured) may prove key, however I think it will require modification. Any thoughts?

I'll try and post some transom shots at the weekend - so you have a better idea of the angles I have to take into account when fitting.

ian parkes · 14 March 2008, 01:39

i found a transom bracket similar to that at the weekend , exept it has a dovetail plate on the transom end so it can just be dropped on and off . i can send you some pics of it if thats the way you need to go.

i don't even have enough room to leave the bracket in place .

Got sell the hinged one i just bought now .

spartacus · 16 March 2008, 22:33

Quote:

I tried to fix a 4hp Mercury, but ther wasn't enough space for that little engine. The solution will be to fix a bracket to the hull and store the auxillary engine inside.

I have thought about this too. I held the auxilliary engine in position on the transom over the weekend, and although it's tight there is enough space at hard-lock both ways. I plan to fit it on the port side, as I have a stern light and flag on the starboard which is all wired in.

If you were storing the engine - would you custom make some sort of bracket inside the boat? The only place I can see it would be out of the way is behind the bench seat. (see illustration)

My only concern with the auxilliary engine on a transom bracket is the vibration - coming of a big wave, etc, which could damage the tilt mechanism, even although I'd probably strap it down for extra rigidity.