How does your auxilliary perform?

[Crocodile]

Hello All,

I am after some real-world results from those who use an auxiliary motor.
Does anybody use a high-thrust Yamaha or a long-shaft Honda on say a 17 foot half cabin?
If so how does it perform?
How fast does it go?
Is a sustained six knots a reasonable expectation?
I am well aware of the concepts of hull-speed for 16' waterline (√16*1.34=5.36knots).
I am never getting on the plane.
I have been unable to find manufacturer's performance bulletins.
There are some vague comments on Hull truth.

In anticipation, thanks.

[Noelm]

6 knots might be a tad optimistic, most auxiliary motors are just better than rowing, in fact the day of the auxiliary is slowly dieing altogether

[littlejim]

My boat is shorter at 14 ft.
I have a 6HP johnson (2str) on an adjustable (drop down) mount. (earlier on had a long shaft, but it was a PITA with the drop down mount.)
This pushes the boat at about 4-5 MPH.
These days gets occasional use for trolling.
In the early days got me out of the poo on several occasions when the big motor wouldn't start.
Cleaning the starter solenoid contacts eventually solved the big donks problems.
The cogniscenti (later) told me I could have shorted the solenoid contacts to get a start. (Now you tell me.)
Wouldn't personally go out without it strapped on, but the RVCP are also there if you get in the poo, so it's up to you choice wise.

[Noelm]

Why would the long shaft be any harder to use with the bracket? just look at the boats launching at the ramp these days, be very lucky to be 1 in 50 would have an auxiliary.

[fishing111]

Crocodile a lot of Tasmanians seem to run them, might be worth joining a Tasmanian based forum to get a bigger audience if you can't get real world performance here.

[GBC]

If you prop a 9.8 correctly you're going to get awfully close I'd think on a 17 footer. Id think a long shaft is going to cavitate a lot less if trying to push into a bit of chop.

[swof63]

Crocodile a lot of Tasmanians seem to run them, might be worth joining a Tasmanian based forum to get a bigger audience if you can't get real world performance here.

Yes Tasmanians seem to have a thing for having two of things that most people make do with one......

cheers

ps. Make sure the sum weight of both motors doesn't exceed the weight rating of the transom.

[Bustedoff]

I had a four stroke 6hp Johnson as a trolling motor on my 525 fibreglass boat (Buccaneer) because it hardly used any fuel compared to the 115 Johnson 2 stroke main engine. It was fine in calm water with little current and would push along at approx. 7kph. It was a single cylinder so vibrated pretty badly, I ended up using car rubber suspension bushes in the motor mount which improved this a lot.
In any kind of sea or current it was a bit useless. If I did it again I'd go for a small twin cylinder for the extra power and low vibration.
Cheers

[ranmar850]

Very old school, really a hangover from the bad old days of unreliable old two strokes. The reliability of modern motors has largely made them redundant. They always had the issue of having the prop out of the water half the time in any kind of sea due to being mounted too far from the centreline and rolling in a beam sea. And being used so infrequently that they wouldn't start if you did need them? Do you really need one? Is your main motor unreliable? if not, just something else to get in the way fighting a fish around the transom? And no, I'm not some young smart*rse, been through it all, just don't think they really are necessary anymore unless your motor is so unreliable you shouldn't be putting to sea in it?

[billfisher]

There have been a couple of boat capsizes off Sydney recently close to the rocks. At least one of them was due to motor failure. In theory an auxiliary could have prevented the accidents. I am not sure if the new high tech motors are more reliable than the carby two stokes. They are more complex, rely on computers, have fuel systems including injectors which are less forgiving to bad fuel, especially water contamination.

The prop should not be out the water given that you are doing displacement speed so the boat will be sitting lower in the water. They are not that hard to fish around given a rod length is six feet or more and the motor only sticks out a couple of feet. The ignition systems are very good on small two stokes these days - mine starts first or second pull after months of not being used. Just make sure you service them the same time you service the main motor.

[scottar]

Don't have one on the current boat (touch wood) but did have one on the last boat that got me out of trouble through no fault of my own - boat upstream of me let about 100m of mono wind itself into the prop on the main in the current. Stuff happens - the next motor to crap itself prior to being run in sure won't be the first - or the last. Just wish I had it when the main on that boat decided to let a bearing cage go and lunch itself while under warranty. If you boat in areas that are remote where help is either a long way off or simply not contactable, it makes sense to be able to self sufficiently get yourself out of whatever sticky mess you managed to get yourself into. There are valid points for not having one but they will all be forgiven if you need it one day.

As for performance, it was an old 7.5 rude longshaft on a 4.5m tinny - mounted with a reinforcing plate directly on the transom on one side - prop was below the bottom of the hull but at much over 4-5 knots it would cavitate and carry on - really wasn't happy but didn't have the same sort of propping that the high thrust yammy does either

[billfisher]

Mine has got me out of trouble several times or at least has enabled me to fish in the bay for flathead instead of going home. I got a high thrust prop for it (different pitch). It actually goes slower with this prop but is much better for the motor (allows it to rev instead of lugging). It's an 18 hp Tohatsu on a heavy 5.4m glass boat and I get about 5 knots. It's a short shaft on a stainless steel folding bracket. I think stainless brackets are the best, make sure it is rated for the weight of the motor and has springs to help you lift the motor up. The main motor is a 1992 model two stroke which as I said has let me down a few times. An extension handle for the tiller arm is handy.

[Spaniard_King]

10hp high thrust Honda would get you 6 knots

[Lovey80]

Just buy a cat and be done with it

[littlejim]

Noel,
even with the adjustable mount fully up it was always dragging in the water.
The normal length shaft is above the water when the mount is in its up position.
With the mount lowered the standard leg sits perfectly.