Auxillary Engine advice

TomKat · 19 January 2012, 12:45

I have a 4.8m Rib with a 75HP Engine so not huge amount of room. I had a wee 2HP Yam shortshaft and it pushed the boat but not in wind so I sold it last night. When tilted up it did not hit the water. And when down it hit the water OK.

My question is should I be buying a short sgaft or long shaft? If long shaft will it clear the water when tilted up?

Running at the budget end of the boating scale I figure an aux is a good idea!

Cheers for tips.

pic of transom area

kerny · 19 January 2012, 13:17

I would say short shaft, long would be dragging in the water when on tilt. Looking at your pic there doesn't seem to be a lot of room on the transom, maybe adding an aux bracket might be a good idea. A 3.5 would be a good size engine for it.

clydeoutboards · 19 January 2012, 15:18

Hi

I would go to your local dealer and ask for a test of the honda 2.3 as this would not o hang of the back need to hang off the back unless you needed to use it and he could check the lengh needed for you.

this pushes out a lot more than an old 2hp engines so worth a try and weighs 12-13kg depending on short or long shaft.

If you feel it is not big enough the tohatsu is the same as the merc / mariner at the smaller sizes but is cheaper and enjoys cheaper spares.

Dave

TomKat · 19 January 2012, 15:41

cheers chaps, the wee honda might work, a mate has one for his tender might be worth a test. I assumed it would be the same as the old Yam but worth a try.
Not bothered about badge - more price/tightness orientated!

hadd · 19 January 2012, 18:37

Quote:

Originally Posted by TomKat

cheers chaps, the wee honda might work, a mate has one for his tender might be worth a test. I assumed it would be the same as the old Yam but worth a try.
Not bothered about badge - more price/tightness orientated!

Hi Tomkat, i had a 4hp sail drive long shaft on this rib last year it pushed it along at 6knot, i had the engine on a bracket & never hit the water, here,s pic

spartacus · 19 January 2012, 20:46

I've had back-up engines on both my boats. First a Tohatsu 3.5hp long-shaft (2-stroke) on a Zodiac Pro, and currently a Mariner 4hp (2-stroke), again long-shaft. I had a Plastimo auxilliary bracket before on the Pro, but never again. Thing use to shake like a bag of tools.

I could probably get by with a standard-shaft auxilliary, but the long-shaft still clears the water if you secure with a ratchet strap and it's under tension.

A Mariner 4hp with internal tank will give you around 45 minutes run-time. You can carry a 4.5 litre (1 gallon) pre-mix spare tank on board. I was looking for a Yammie 4hp that can connect to main fuel tanks - but they're pretty rare.

TomKat · 19 January 2012, 21:52

cheers chaps, might be worth setting a long shaft on for a look! What do you mean by rachet strap for securing?

Chris · 21 January 2012, 07:43

The main thing you want to ensure is that with the engine tilted down the prop is completely below the bottom of the transom, otherwise you won't get the full performance out of the prop

spartacus · 21 January 2012, 09:04

Quote:

Originally Posted by TomKat

cheers chaps, might be worth setting a long shaft on for a look! What do you mean by rachet strap for securing?

Most small outboards when tilted in the 'up' position will have a degree of play, so you can imagine what they're like underway or at WOT. The tilt mechanism won't take this kind of abuse for long.

I fitted a stainless-steel u-bolt on the transom leg/support. I use a ratchet strap secured around the auxilliary engine (under the cowl) and connect it to the u-bolt, then ratchet it so it's under tension. The auxilliary stays clear of the water, is tight as a gnat's chaff, and is rattle free. Easy enough to deploy when required. In an emergency I'd cut the strap.

TomKat · 22 January 2012, 18:34

cheers Spartacus, took a chance on a long shaft 5HP Mercury 2 stroke with 30 hours on it (allegedly!). with your strap tip I should be able to tilt it up enough to clear the water. If not look out for another ob int he for sales!

I have not made the a fram yet so should be able to squeeze it in, I hope...

hadd · 22 January 2012, 18:37

Quote:

Originally Posted by TomKat

cheers Spartacus, took a chance on a long shaft 5HP Mercury 2 stroke with 30 hours on it (allegedly!). with your strap tip I should be able to tilt it up enough to clear the water. If not look out for another ob int he for sales!

I have not made the a fram yet so should be able to squeeze it in, I hope...

http://www.rib.net/forum/attachment....8&d=1327001825

TomKat · 22 January 2012, 18:42

Engine pic

hadd · 22 January 2012, 18:59

Quote:

Originally Posted by TomKat

cheers Spartacus, took a chance on a long shaft 5HP Mercury 2 stroke with 30 hours on it (allegedly!). with your strap tip I should be able to tilt it up enough to clear the water. If not look out for another ob int he for sales!

I have not made the a fram yet so should be able to squeeze it in, I hope...

Hi tomkat this is my 5hp long shaft on my last boat never went in the water when cruising

TomKat · 22 January 2012, 19:16

Cheers Hadd, was it mounted on an extension plate that effectively raised the transom? Hard to tell from the pic. Seems quite a big plate underneath it.

hadd · 22 January 2012, 19:28

Quote:

Originally Posted by TomKat

Cheers Hadd, was it mounted on an extension plate that effectively raised the transom? Hard to tell from the pic. Seems quite a big plate underneath it.

heavy duty Engine bracket from boat jumble , I just left the bracket as it is, just made sure all the nuts & bolts where all solid so the bracket won't move, With the long leg you can just drop the engine & away you go

& it stops the rattle when you put a ratchet strap on, i strap it to the locking pin when the engine is lifted up it won't move at all .

TomKat · 22 January 2012, 19:31

cool, picking engine up later this week so will no doubt be back on but that pic of yours is very useful. Pretty sure it can be made to fit OK but no point reinventing the wheel!

kerny · 22 January 2012, 19:42

If you ever need another one in the near future, at least that you will know that any size should fit. Same make of rib.

TomKat · 22 January 2012, 20:13

Quote:

Originally Posted by TomKat

Engine pic

As an aside would this work on a SIB? Was thinking of a Yam 260 to throw in the back of the campervan, A short shaft would be best but wondered if I could use this at a pinch?

hadd · 22 January 2012, 20:15

Quote:

Originally Posted by TomKat

As an aside would this work on a SIB? Was thinking of a Yam 260 to throw in the back of the campervan, A short shaft would be best but wondered if I could use this at a pinch?