Re-engine or go for twin-engines

[FreeTrader]

Dear all,

I'm close to finishing my first season ribbing, and I've covered best part of a 1000 miles this year, which is more than the previous 6 years sailing.

My rib is an 8.5m Scorpion with a 225 Opti. Both have been fantastic apart from the odd glitch with the Opti (2001, 500 hrs). I've progressively pushed my comfort zone, and now often out in F5+, which is fine, but not great if your engine goes. So I think I've got two options:

1. Re-engine with a Suzuki 300, add dual fuel filters, spare tank, and separate battery/electric install. In my (limited) experience, I reckon it's usually fuel or power that stops boats.
2. Go all out for a new or nearly new twin engined Scorpion.

Downside for no.2 is it's a lot of cash, both upfront, and in terms of running costs.

What do you wise ribbers think?

Atb,


Phil

[pop]

why not put twins on yours

[BogMonster]

If I had the money (highly unlikely) I'd love something with a decent set of twins on it both for the safety factor but also the pure appeal of lots of engines

One engine is still one engine if it stops...

[codprawn]

I am in a very similar dilemma with my boat - I really love my suzuki DT225 - it's awesome but my hull is just crying out for more power. I really don't want to go for 2x engines. The extra cost and extra fuel are one thing but also the extra weight hanging off the transom will spoil the balance. My boat lands nice and level off big waves unlike most of the twins I have seen.

I already have 2x everything on fuel and 2x batteries - also an aux 15hp(not fitted yet). I WAS looking at the Suzuki 300hp 4 stroke but now something else has taken my fancy - the new Mercury racing 300xs. It is a good old 2 stroke but with Optimax technology - even better it is very light - only 225kgs!!!

[benc]

Originally Posted by codprawn

....also the extra weight hanging off the transom will spoil the balance. My boat lands nice and level off big waves unlike most of the twins I have seen.

My boat flies and lands nicely, my console is quite far forward, which helps. But the back of the boat coming down first isn't always a bad thing - less chance of landing nose into a wave.

You can sort balance by adding ballast in the bow... so I don't think balance is neccessarily a good reason not to go for a twin setup.

If I was planning on taking the boat out in rough weather a lot, there is no doubt in my mind that I'd go for twins. I believe an auxillary is pointless in bad weather - unless its a decent size, it probably wont push you against the wind and tide, and if it does - it would be an extremely long ride home.

With my twin engine setup now (twin 150hp Yamaha HPDI) and the 7.5m Tornado, I get about 53-54 knots top speed. The hole shot is extrememly good, it pops out of the water onto the plain in a couple of seconds and is off ... probably up to about 40 knots in 5-7 seconds (I haven't timed it, but its bloody fast!). I have tested the boat with a single engine, with the other tilted up, and I get 30 knots - which is a very good "get me home" speed.

Theres a couple of downsides to twin engines - two lots of maintenance costs, and a larger fuel consumption - which might mean increasing the size of the tanks on your boat. I currently have 180litres of fuel (in two 90litre tanks)... which will in theory of me doing 60l/h at about 40 knots, will get me 120nm which isnt a bad range, but I want more.

[BogMonster]

Originally Posted by benc

If I was planning on taking the boat out in rough weather a lot, there is no doubt in my mind that I'd go for twins. I believe an auxillary is pointless in bad weather - unless its a decent size, it probably wont push you against the wind and tide, and if it does - it would be an extremely long ride home.

That's sort of my feeling because the Law of Sod indicates the main fan will stop at the worst possible moment (bit like the same law applied to a single engined aeroplane which indicates it will stop over water....).

I don't know much about balancing a boat when its airborne but like most things I think you can see when it's been done right. The video link somebody posted of a Zodiac CZ7 a few days back was awesome, I couldn't believe the way that thing just whistled across a rolling swell with literally just the props in the water for half the time, every landing was perfect, the balance to do that must have been perfect, and it had twins. If I ever get an obscene amount of money from anywhere I am going to buy one of those. No question

[codprawn]

Look again - a few of the landings were fairly stern end heavy. I know I watched that video about 100 times!!!

If you thought that was impressive watch this

http://www.boomeranger.fi/images/ind...conditions.mpg

Right at the start you will see the boat lands VERY stern down - but it is running unladen - all the seats in the front would normally be filled with troops which would balance it out far better.

It is only at the very end when it comes alongside the support vessel you realise just how rough it REALLY is!!!

Impressive holeshot isn't only the preserve of twins - my boat jumps like a scalded cat because of the 19" 4 blade prop - limits my top speed to 41kts thopugh - will try another prop this weekend....

[benc]

Originally Posted by codprawn

Impressive holeshot isn't only the preserve of twins - my boat jumps like a scalded cat because of the 19" 4 blade prop - limits my top speed to 41kts thopugh - will try another prop this weekend....

I'd like to see it against mine

You should come venture out in the solent sometime

[codprawn]

Originally Posted by benc

I'd like to see it against mine

You should come venture out in the solent sometime

Can't stand those horrible little waves - much prefer a big rolling Atlantic swell.

[pathalla]

Consider this: if you have two additional passengers seated in the aft of your boat, that could probably equal the weight of a additional motor. I feel a twin engine boat cuts/pushes through the waves better due to the extra prop (more bite). I don't notice the extra weight in the stern affecting the attitude or performance of the boat negatively, and I think the boat pitches less port to starboard underway due to two props driving it. In a boat 8 meters or greater in length you probably won't negatively affect its ride by adding another motor, (making it stern heavy). If you are thinking about switching to twins an outboard bracket makes a lot of sense, it gives you a full height transom, (no motor cutout) the motors can be trimmed all the way out of the water, it adds additional bouyancy to the stern of the boat, and it adds length to the hull, this benefits twin and single engined boats. I don't see brackets on U.K. based ribs, not sure why this is so as brackets are a very common feature on boats here in the states, they work well!
I would think someone could make a lot of money building and selling outboard brackets to the market over there, just a thought...

[codprawn]

I have my engine mounted on a transom jack - with 10" setback - it's mainly on racing boats you see them though!!!

Fair comment about the passengers but they don't hang off the boat behind the transom - just my observations from watching every RIB video I get my hands on!!!

[pathalla]

Your boat could handle a pair of twins Cod, couple of 250's, then she would really fly!! Have you noticed people never say... I"m thinking of taking one engine off my boat. Or... I would like to put a smaller motor on my boat.
It just doesn't work!!

[BogMonster]

Originally Posted by codprawn

Look again - a few of the landings were fairly stern end heavy. I know I watched that video about 100 times!!!

If you thought that was impressive watch this

http://www.boomeranger.fi/images/ind...conditions.mpg

Right at the start you will see the boat lands VERY stern down - but it is running unladen - all the seats in the front would normally be filled with troops which would balance it out far better.

It is only at the very end when it comes alongside the support vessel you realise just how rough it REALLY is!!!

Impressive holeshot isn't only the preserve of twins - my boat jumps like a scalded cat because of the 19" 4 blade prop - limits my top speed to 41kts thopugh - will try another prop this weekend....

Yes but the ones where it was a stern heavy landing was when taking off at a very high angle! Put it this way, it flies exactly the way I would like my perfect boat to fly and I still really want one

Have seen the other video before, quite impressive too. Funnily enough I also seem to be accumulating a goodly collection of RIB videos, quite a few from the Blue Ice website, Richard's ones are excellent

41 kt is a bit slow codders even my old Humber with its swiss cheese tubes gets to 39kt with a lawnmower engine on the back

[Searider]

How about puting another Opti 225 alongside your existing one. Cheapest way of getting a twin installation. - I guess it depends if your boat is suitable for two engines.

Not sure if the cowlings would match up - but you might be able to fit a new set of cowlings to fit your old engine to make it all look good?

[codprawn]

Yup 41kts is slow - different prop on soon - trouble is from one extreme to the other - 19" to a 24" - won't know until I try though!!!

[Downhilldai]

Originally Posted by codprawn

Yup 41kts is slow - different prop on soon - trouble is from one extreme to the other - 19" to a 24" - won't know until I try though!!!

Cod,
Have you been to see Tot in SD Marine? He may have something in between? I think going from 19" to 24" will be taking you from one extreme to the other.

[jellis]

Originally Posted by BogMonster

Yes but the ones where it was a stern heavy landing was when taking off at a very high angle! Put it this way, it flies exactly the way I would like my perfect boat to fly and I still really want one

Have seen the other video before, quite impressive too. Funnily enough I also seem to be accumulating a goodly collection of RIB videos, quite a few from the Blue Ice website, Richard's ones are excellent

41 kt is a bit slow codders even my old Humber with its swiss cheese tubes gets to 39kt with a lawnmower engine on the back

I have been out in some pretty decent seas as well as long rolling swells and it is very stable in both and lands just fine and I have twin 175 Etecs on the back - if you are ever in North Wales you are very welcome to come out and find out for yourself


ATB

Jon

[codprawn]

Originally Posted by Downhilldai

Cod,
Have you been to see Tot in SD Marine? He may have something in between? I think going from 19" to 24" will be taking you from one extreme to the other.

I only bought the 24" because £49 for a like new stainless prop just HAD to be worth a try!!!

Did ask him a while ago but he said he'd sold them all off cheap!!! Will have to give him another try - thanks for the tip.

[BogMonster]

Originally Posted by jellis

I have been out in some pretty decent seas as well as long rolling swells and it is very stable in both and lands just fine and I have twin 175 Etecs on the back - if you are ever in North Wales you are very welcome to come out and find out for yourself

I'd love to but I've only ever been to Wales twice in my 33 years so it may be a while

Thanks for the offer

[jellis]

Originally Posted by BogMonster

I'd love to but I've only ever been to Wales twice in my 33 years so it may be a while

Thanks for the offer

Thats more often than i have been to the Falklands!!!!