Long-/shortshaft, aux.power for RC 4.8 ?

ragbar · 29 June 2015, 23:57

Hello,
I want to buy an auxiliary 2-stroke for my Ribcraft 4.8.

How much power do I Need ? Normalshaft ok, or better longshaft ?

Greetings

Eric

jeffstevens763@g · 30 June 2015, 08:57

hi Eric
common thoughts are 1hp/m and depending on what you want if you want a get you home go for the largest hp you can fit otherwise a 5hp would give you peace of mind and keep you safe i had a 4hp on a 6m rib pushed it at 3-4 knts in good conditions better than oars!.

alystra · 30 June 2015, 09:51

I have an old 3 hp Johnson 2 stroke standard shaft aux for my 5.3m Humber. It has saved my bacon once, being used in earnest after a breakdown in the Sound of Jura.

2.5 - 3 knots. However, though the cavitation plate is below the hull, the turbulence around the transom when moving at such a slow speed means it ventilates and loses thrust at full throttle. I have to sit on the tube right beside it to get it to bite, so can't sit and steer with the main engine.

A long shaft would, I think, be so much better.

jeffstevens763@g · 30 June 2015, 11:39

Quote:

Originally Posted by alystra

I have an old 3 hp Johnson 2 stroke standard shaft aux for my 5.3m Humber. It has saved my bacon once, being used in earnest after a breakdown in the Sound of Jura.

2.5 - 3 knots. However, though the cavitation plate is below the hull, the turbulence around the transom when moving at such a slow speed means it ventilates and loses thrust at full throttle. I have to sit on the tube right beside it to get it to bite, so can't sit and steer with the main engine.

A long shaft would, I think, be so much better.

you could sort that with the fold up type of aux bracket which allows the engine to be quite away from the transom and then steer from the aux or tighten the slew knob on aux and use main engine to steer

ragbar · 30 June 2015, 21:19

OK guys,
I've bought a nearly new 4 hp Suzuki 2 stroke with normal shaft for auxiliary today.

I think a long shaft would fit a bit better the needs, but this little engine was to have for a laughing price so i had to catch that one.

I will mount it on the transom without that helping plate first to have a look how it goes, if it doesn't fit, I'll buy that auxiliary plate for the transom.

Thanx.

Ajt108 · 01 July 2015, 10:47

Hi. I have a 4.8 RC and a 4hp standard shaft and it works well as an aux. You will hopefully be able to fit it along side you main engine. See the picture below. This means it's not on a bracket so it won't bang around as much. I fit mine over one of the transom bolts and it fits well. One thing to be careful of is (abs there isn't much space) if the aux turns in its side it can rub up and down on the tube. So best to ensure can't happen when fitting. It might only happen when lying on one side. I put a wear patch in the tube where it would rub if it does.

paintman · 01 July 2015, 19:19

Quote:

Originally Posted by ragbar

OK guys,
I've bought a nearly new 4 hp Suzuki 2 stroke with normal shaft for auxiliary today.
Thanx.

If it's like the one pictured in this link I've got one - long shaft.
Winnow - Further images and information.
I use it as the auxiliary on a 17' Dory Sportsman hard boat. Very good it is too. Can't tell you off the top of my head what speed it drives the boat at flat out but I use it for trolling & it's got me in once without any difficulty against tide & wind when the oil feed on my main engine split.

spartacus · 01 July 2015, 21:51

I opted for a long shaft 4hp auxiliary. This picture illustrates it pretty well, so underway its out of the water. You can mount straight onto the transom.

Couple of things, use an anchor point on the transom knee to ratchet it down to stop it from bouncing. Lastly, rinse it with fresh water regardless of whether or not it's used. A long-shaft auxiliary will still suffer from salt build up. Don't ask me how I know!

Ajt108 · 01 July 2015, 23:32

+1 for ratcheting it down

when i added an aux to mine spartacus kindly helped me find my engine and gave the same advice. Only when I was underway did i notice how useful the advice was!

Ajt108 · 01 July 2015, 23:35

also if you do end up putting it on an aux mount instead of directly on the transom (advise against this if possible) then make sure you have a lead from the aux tied onto the transom on a strong point. My father went out this past week in his boat and when the aux started up it snapped itself off the aux mount and only didnt end up on the bottom of the loch as he had a line from it to the boat!

ragbar · 03 July 2015, 00:50

Thank you all very much for your advices.

Today I recieved my Suzi 4 from the seller, tried to put it directly onto the transom of my boat and found one towing eye is sitting where the aux' bracket has to be.

No Problem i'll find a solution for that, but place isn't very much beside my Suzi Dt 55 main engine (+ my old teleflex steering), and also my sonar sounder is disturbing, but------nevermind.

If it's possible I' ll mount the aux without that extra plate directly on transom and try here in the River (Rhine, big+shallow& dangerous) how it all works together.

Paintman: exactly that one I bought, but with normal shaft. Nice engine.

Spartacus: Is that a teleflex steerbord on your Twatso, too?

Cheers

Eric