Small auxiliary engine

simonafloat · 02 March 2016, 19:23

Hi all

I have been trying to find a small 2 stroke engine as a backup on my sib. I hadn't realised that even some 4hp engines have the option of running off an external tank, which I think could be quite handy for me.
Can anyone suggest some models I could look out for with this feature? Or does it appear on many old models as an optional extra.

Cheers

Simon

simonafloat · 02 March 2016, 19:58

Quote:

Originally Posted by simonafloat

Hi all

I have been trying to find a small 2 stroke engine as a backup on my sib. I hadn't realised that even some 4hp engines have the option of running off an external tank, which I think could be quite handy for me.
Can anyone suggest some models I could look out for with this feature? Or does it appear on many old models as an optional extra.

Cheers

Simon

just a thought, I own a little single cylinder mariner 3.5 2 stroke, is there any way to convert it to run off an external tank? I'm assuming no as it's fed by gravity.

spartacus · 02 March 2016, 20:26

Tohatsu outboards from 4hp up (2-stroke) feature option of connecting to external tank. Trouble is finding one. Smallest Yamaha (as far as I'm aware) would be 6hp. http://www.tohatsu-uk.net/EnginesNew/2StrokeFrame.htm

No idea about converting existing outboard to run off external tank.

jeffstevens763@g · 03 March 2016, 07:25

Suzuki do a conversion basically it fits left-hand side front of the engine its not the same as the round Suzuki connector its the bayonet type i have one hear that i didn't use if of interest. i did my 4hp with a round connector with a quarter turn valve to shut the internal tank off cost £20 ish

cheers

beamishken · 03 March 2016, 07:32

4 & 5 hp single cylinder 2 stroke yamaha is the one to get probably the best engine you'll find at this size

paintman · 03 March 2016, 07:38

My backup is a Suzuki DT4 4hp & that has the fittings for an external tank.
Bear in mind that these small 2-strokes are premix so if your main is 4-stroke, runs a different premix ratio or is oil injected (mine) you're going to need a separate fuel supply anyway.
Likely the fittings may not be the same as your main.
A 5 litre container doesn't take up that much room.

Fenlander · 03 March 2016, 12:09

If you want an aux on an Aerotec then the smallest/lightest possible model is needed. Is your 3.5 like the narrow 2/2.5hp models with no gears and throttle on the cowling? That's about as large as you want to go. These will need to run off their own tanks and as said above a 5l emergency can is no hardship to carry.

Once you step up to the 4hp and above motors that can take an external tank they're getting a bit large.

This is the sort of thing I'd be looking for...

https://m.youtube.com/watch?v=hf2jTKMFL2Y

jeffstevens763@g · 03 March 2016, 13:47

Suzuki just brought out new portable engines 4,5,6hp @ 23,5 kg can be stored on three sides port starboard or front gravity fed tank.

cheers

Stigomery · 03 March 2016, 17:47

I've been pondering this 'aux engine' question. Having lugged a back-up with me on my first outing in the new Honwave and found it to be nothing more than a PITA - OK so it is an elec trolling motor that had to sit in the boat along with a 110AH leisure battery... but regardless of form... does one really need this if venturing no further than 1 mile off shore? Do people do this normally?

(I can see the merits if out on a solo expedition)

jeffstevens763@g · 03 March 2016, 18:05

Quote:

Originally Posted by Stigomery

I've been pondering this 'aux engine' question. Having lugged a back-up with me on my first outing in the new Honwave and found it to be nothing more than a PITA - OK so it is an elec trolling motor that had to sit in the boat along with a 110AH leisure battery... but regardless of form... does one really need this if venturing no further than 1 mile off shore? Do people do this normally?

(I can see the merits if out on a solo expedition)

Would it be any good in wind and tide the trolling motor?

Fenlander · 03 March 2016, 18:41

Stig this is a very personal thing so it's what I do not what you might want to do but I will never use an aux engine on a sib because....

We don't go on expedition type outings over several days so are just operating within a sensible radius of wherever our "base" is that day. I always have crew so assistance with oars/paddles is available. I plan our trips with regard to wind direction and safe refuge in emergency. I have never had an outboard fail in many decades... possibly as I undertake careful pre-emptive maintenance.

When I think back to the 60s I was trolling about abroad as a 10yr old in a grp dinghy with a Seagull and no lifejacket or any way of alerting my folks if I'd got in a muddle. The main craft that dinghy was tender to had neither GPS nor radar and we were to and fro France often on night crossings without the slightest concern.

So I reckon I take the best care possible of self and crew within sensible reason... and an aux on a sub 4m craft isn't part of that.

simonafloat · 03 March 2016, 19:15

Quote:

Originally Posted by Fenlander

If you want an aux on an Aerotec then the smallest/lightest possible model is needed. Is your 3.5 like the narrow 2/2.5hp models with no gears and throttle on the cowling? That's about as large as you want to go. These will need to run off their own tanks and as said above a 5l emergency can is no hardship to carry.

Once you step up to the 4hp and above motors that can take an external tank they're getting a bit large.

This is the sort of thing I'd be looking for...

https://m.youtube.com/watch?v=hf2jTKMFL2Y

That's what I've got, or rather this one Mariner 3 3 hp Outboard Motor FOR SALE from Newcastle New South Wales @ Adpost.com Classifieds > Australia > #298 Mariner 3 3 hp Outboard Motor FOR SALE from Newcastle New South Wales ,free,australian,classified ad,classified ads,secondhand,second ha

I spayed mine matt black years ago, mine was branded 'force' but is clearly a mariner/mercury, no gears, light as a feather. Will use that. It'll be fine on the aerotec transom.

Stigomery · 03 March 2016, 21:32

Quote:

Originally Posted by jeffstevens763@g

Would it be any good in wind and tide the trolling motor?

It would get us back to shore in moderate conditions, it wouldn't get us back to base... and it would struggle against strong wind/tide but would supplement rowing :-)

The trolling motor I have is equivalent to about 1.5hp so the crudest of back-ups. We use it on our Canadian canoe and can shift 4 of us plus dog, picnic, etc. upstream at about 4-5kts.

Stigomery · 03 March 2016, 21:34

Quote:

Originally Posted by Fenlander

I was trolling about abroad as a 10yr old in a grp dinghy with a Seagull and no lifejacket or any way of alerting my folks

Ditto... But it was the 80s and back then I didn't have 2 small kids and a wife to worry about ;-)

9D280 · 04 March 2016, 11:42

the 1968-74 Johnsorude had a tank option! I have been toying with adding it with a changeover valve (internal / external) but it would involve total dissassembly of the power head to drill the hole to power the fuel pump.....

The way I got round it - An open ended hose to connect to the end of my main engine fuel line - and just fill the tank manually with the primer bulb......