back-up engine

Jimbob · 25 October 2004, 14:55

Well its finally happened after lots of searching and lots of helpful tips from this forum. I am now the proud owner of a 7.5 Scorpion rib.

Actually to anybody looking for a rib this is a good time, many people think about selling, many becuase they did not use it much and considered it alot of money just sitting there.

Anyway, my question, i am going to get a back-up engine, i was thinking 5-6 hp just to get me home, the reason i say this hp is because MBM did a section on this quite recently

Alan · 25 October 2004, 15:06

Congratulations! An excellent buy if I do say so myself. What year & engine?

5-6hp will be fine as an aux. I had a 6hp Tohatsu & I think Richard B now has a 5hp on the same boat. You wont go anywhere fast or neccessarily against the tide but it will move you along. For max endurance and min hassle go for a 4 stroke and get it plumbed into the main tank. (assuming you have an oil injected or 4 stroke main engine).

HTH,
Alan

codprawn · 25 October 2004, 16:57

Quote:

Originally Posted by Alan

Congratulations! An excellent buy if I do say so myself. What year & engine?

5-6hp will be fine as an aux. I had a 6hp Tohatsu & I think Richard B now has a 5hp on the same boat. You wont go anywhere fast or neccessarily against the tide but it will move you along. For max endurance and min hassle go for a 4 stroke and get it plumbed into the main tank. (assuming you have an oil injected or 4 stroke main engine).

HTH,
Alan

I was told NOT to use the main tank as if it is fuel probs that have caused your main engine to stop it will do the same to the aux.

ashbypower · 25 October 2004, 17:07

Quote:

Originally Posted by codprawn

I was told NOT to use the main tank as if it is fuel probs that have caused your main engine to stop it will do the same to the aux.

Whole heartedly agree, been there done that and we suffered. Our dive club boat had a common fuel tank, fuel contaminated

bingo no engines main or Aux Doh!!

Brian.

Jono · 25 October 2004, 17:27

mmm.. yup, if it's a fuel problem that stops your main. What if it's something else and your miles from base? If you have the OPTION of using either a separate tank or plumbing into the main, is that not better. Wouldn't you feel a chump running the aux dry, 10 miles from home whilst sat on 100 litres of unreachable fuel...

ashbypower · 25 October 2004, 17:31

Jono, whilst I agree I think you miss the point, you don't hed for home but to a safe haven to sort the prob. Sitting on 100 liters of contaminated fuel and 2 engines 10 miles from home is equally foolish.

All IMHO of course.

Brian

Manos · 25 October 2004, 18:20

Quote:

Originally Posted by Alan

For max endurance and min hassle go for a 4 stroke and get it plumbed into the main tank. (assuming you have an oil injected or 4 stroke main engine)

... and what happens next if it happens that the main engine seases due to water (say hypothetically) in the main tank. Your aux engine goes in the bin too and start using the flippers or get down and push the boat?

For the Scorpion I think a Tohatsu 5bhp 2stroke (I am not into the 4 strokes yet) with its own little tank on it will be OK...ish. I do do not know if the bigger Tohatsus have own tank but the bigger aux engine you get the better for a boat of that size and weight will be.

Nice choice of a good seaworthy hull and hope that you enjoy her.

Richard B · 25 October 2004, 18:52

Didn't some fellow in a yellow RIB do quite a lot of miles on an auxiliary diesel from time to time a couple of years ago? I wonder whether he used a little portable tank or tapped off a main tank...

Alan · 25 October 2004, 19:10

Quote:

Originally Posted by Richard B

Didn't some fellow in a yellow RIB do quite a lot of miles on an auxiliary diesel from time to time a couple of years ago? I wonder whether he used a little portable tank or tapped off a main tank...

Nah he carried a collection of jerry cans or aux fuel tanks which is of course what you have to do to be absolutely postively sure that your aux will work. Along with running it everytime you go out rather than leaving it bolted to the transom unloved and wondering why it wont start when you need it

I hear the arguments about not running from the main tank but personally if I have an aux I want to be able to run it for as long as I can.

Richard B · 25 October 2004, 19:14

Quote:

Originally Posted by Manos

...keep every option open...

Jono · 25 October 2004, 19:19

Quote:

Originally Posted by ashbypower

Jono, whilst I agree I think you miss the point, you don't hed for home but to a safe haven to sort the prob.
Brian

true, true,.... but exactly how close is a your safest haven halfway across to the Channel Islands.. ? Thanks, but I'll keep the option of plumbing my aux into the main as well as its own 20 litre tank...and keep an eye on my nice and visible water separators...

codprawn · 25 October 2004, 20:13

Quote:

Originally Posted by Jono

mmm.. yup, if it's a fuel problem that stops your main. What if it's something else and your miles from base? If you have the OPTION of using either a separate tank or plumbing into the main, is that not better. Wouldn't you feel a chump running the aux dry, 10 miles from home whilst sat on 100 litres of unreachable fuel...

Fuel would NOT remain unreachable for long if I was desperate enough!!!

Richard B · 25 October 2004, 20:53

Quote:

Originally Posted by codprawn

...I was desperate enough!!!

How far offshore are you planning to travel, my fishy friend?

As we discussed a little while ago, you would perhaps just want to make passage to the nearest VHF or mobile 'phone coverage - or is this a demonstration of independence, or personal pride to make landfall under your own power?

codprawn · 26 October 2004, 00:50

Quote:

Originally Posted by Richard B

How far offshore are you planning to travel, my fishy friend?

As we discussed a little while ago, you would perhaps just want to make passage to the nearest VHF or mobile 'phone coverage - or is this a demonstration of independence, or personal pride to make landfall under your own power?

Independence and pride - would die of shame if I had to be rescued because of my own stupid fault.

Would only call for help if lives were in serious danger - if aux wasn't man enough to push me against a tide I would anchor and wait until the tide turned - probably do a spot of fishing to make it look like everything ok!!!!

Jimbob · 26 October 2004, 07:55

Hi all

It seems i have enought info now so what i will do

1) 5/6hp 4 stroke to keep things simple
2) Spare 20/20 l tank
3) method of connecting to main tank

That should do it. For me its just knowing that i have a back-up. Over the last year i did alot of work on an ex pilot boat with twin engines and sometimes one would give problems, from just stopping in the main channel to all sorts of things, having the second engine proved its worth.

I am sure lots of people dont have a second engine and i'm sure they have not had issues for me its just knowing i have the option

Thanks for the info everybody, i have balanced view

Hightower · 26 October 2004, 17:40

Seems like a sensible approach Jimbob. Only thing I would add is a procedual one, always run the Aux off the seperate tank first untill it's depleated and then switch to main tanks just in case of contamination and make sure your fuel in the Aux tank is replaced on a regular basis.

Good luck with your new purchase and congratulations.

Andy

brucehawsker · 28 October 2004, 22:13

We have tried our 6.5M Solent in the harbour with a 6hp 4 stroke suzuki and found we were better using the main engine as a rudder and keeping the aux locked striaght ahead. We have it set up so as to be able to use either the main fuel tank or the auxiliary. 6hp was fine to manoevre around the harbour, make turns etc. We have reverse mounted the aux. engine. Works well.

DGR · 29 October 2004, 12:49

How do you mean 'reverse mounted'? Any chance of some pics?

I need to get an aux engine - especially with the recent increase in scarcity of RIBs at Fleetwood

- and I'm not sure of the best way to mount it. I'd ideally like it to be there full time - so it's ready when I need it.

Cheers,

Dylan...

swginn · 29 October 2004, 14:17

"Reverse mounted" means mounting the engine with leg inside the boat. I guess the advantages of having it like this are if the tilt lock fails it will tilt into the boat instead of out of the boat (could do a lot of damage at 50kts!!)

I was told before by a buddy who has his mounted like this that it also helps with weight, but if anything I would have thought that most of the engines weight is in the powerhead and so would make more sense to have this on the inside of the boat instead of hanging over the water.

I personally have mine mounted the conventional way with the leg of the engine tied to the a-frame in case the tilt lock fails. It is ready to use, the rope just needs to be untied, or cut if its urgent!! and away you go.

Alan Priddy · 29 October 2004, 14:35

Quote:

Originally Posted by Jono

true, true,.... but exactly how close is a your safest haven halfway across to the Channel Islands.. ? Thanks, but I'll keep the option of plumbing my aux into the main as well as its own 20 litre tank...and keep an eye on my nice and visible water separators...

Depends on where you are heading to but if you are half way to / from the Channel Islands the furthest you will ever be from a safe harbour is 25 miles. In fact, unless you are crossing the Irish Sea to Cork no mater where you go in the UK or Europe you will never be more than 30 miles from land. Still, at 3 knots in open sea it can be a long time. As for the "Yellow" boat. We had to use our wing engine to get back to Singapore when we broke down 200 miles out in the South China Seas. still it gave us plenty of time to think about things! Alan P