Petrol sterndrives?

r mcdonald · 10 January 2009, 04:03

Happy new year everyone.
Does anyone consider installing a petrol sterndrive in a rib over 7 meters anymore,or are outboards and diesel sterndrives the way people are heading? Diesel sterndrives are about 30% more in capital and fuel cost compared to petrol, down here.
regards
rpm

BogMonster · 17 January 2009, 19:20

I would have thought petrol sterndrives miss the obvious advantage of going inboard which is the economy of a diesel engine. You've got the weight anbd space penalty of an inboard installation, and the fuel consumption of a petrol engine...

codprawn · 18 January 2009, 05:06

Well for the same weight as a Yamaha 315hp diesel you can get a 600hp petrol mercruiser like this - I know which I would rather..........

http://www.mercuryracing.com/sterndr...0sci/specs.php

Then again 2x 300XS outboards are lighter again!!!

biffer · 18 January 2009, 09:16

nice bit of kit, just looked at the fuel consumption, scary!!!!

MarkWildey · 18 January 2009, 10:09

Compare the difference in cost of the engine and work out much fuel that equates to and then how many hours per year you'll use the boat.

Maybe petrol is the way to go if your an average boat user!

biffer · 18 January 2009, 10:28

as a commercial operator maybe, done 800hrs on a diesel in 3 seasons still not looking that good, i know where your'e coming from prices of engine and all, but it's of interest that in the states it's the diesels that are cheaper to buy, and it's just ripoff britian yet again rearing it's ughly head, just the same as cars, a number of years ago diesel was cheap because of few diesel cars, they bring out quieter more efficent cars, more people buy them,more diesel purchased, let put the price up, and it goes on, youv'e started me off now, have to go and have a walk the garden!

r mcdonald · 18 January 2009, 10:41

Quote:

Originally Posted by BogMonster

I would have thought petrol sterndrives miss the obvious advantage of going inboard which is the economy of a diesel engine. You've got the weight anbd space penalty of an inboard installation, and the fuel consumption of a petrol engine...

A 260hp petrol sterndrive costs about $23000, a 200 diesel sterndrive costs about $35000.
Petrol cost $1.05 a litre and diesel $1.30 a litre.I would need to use the rib alot before I broke even with a diesel.
I thought for the same weight you can get more HP from a petrol than diesel.
With a sterndrive you can have a swim deck at the stern which may compesate for the room lost in the rib compared to an outboard. and the weight is futher forward and lower with the sterndrive.
If I was to use an outboard,I would possilbly have two motors so the weight would be the same as the diesel sterndrive and the same price aswell.( a couple of 140hp $32000).The petrol sterndrive seem to be the cheapest option except for one 200 to 250hp outboard which is the same price as the petrol sterndrive.
Or is my thinking not quite right?

So thats why I was asking the orginal question about petrol sterndrives.
thanks for the replies
regards
rpm

r mcdonald · 18 January 2009, 10:47

Biffer
quote:"i know where your'e coming from prices of engine and all, but it's of interest that in the states it's the diesels that are cheaper to buy, and it's just ripoff britian yet again rearing it's ughly head"

I am in one of the colonies of Britian (Australia)
regards
rpm

biffer · 18 January 2009, 11:56

i've been a rib manufacturer for years and trust me what happens over there isn't what happens over here, privately i could tell you some stories that would make your blood boil

biffer · 18 January 2009, 12:20

rpm
sorry i got side tracked,i'm with you on inboards and i dont lose any deck space' see pics', not only can i put gear in the engine bay but also on top and the cabin speaks for itself, i've got a few mates over there who say they wouldn't come back, check out us inboard prices it's the otherway round or it used to be, can't think it's changed since the last time i had dealings

Cookee · 19 January 2009, 15:28

Obviously different countries have different prices on engine packages and fuel packages, so direct comparison is useless, but to answer your question I do know of a Revenger Rib with an Ilmor V10 in it - it goes very well too!

codprawn · 21 January 2009, 03:29

Quote:

Originally Posted by Cookee

Obviously different countries have different prices on engine packages and fuel packages, so direct comparison is useless, but to answer your question I do know of a Revenger Rib with an Ilmor V10 in it - it goes very well too!

And it sounds a lot better than a diesel............

http://uk.youtube.com/watch?v=XK-kuGzg4k8

TangoTango · 21 January 2009, 17:08

Having had a cruiser with a petrol outdrive, I would say that if you are going to use a petrol engine, an outboard is far better than an inboard. They are easier to access, cheaper to service and as has been pointed out already they take up no space in the boat. The final nail in the coffin as far as I am concerned is that if you operate in shallow water, lifting up the leg of an outdrive is liable to cause you problems. Although theoretically they are able to be lifted nearly out of the water while running, in practice it can damage the universal joint (or whatever it is called, I think it is like the CV joint on an old Mini) or pull off the gaiters and let water into areas where it should not go.

If you decide on a diesel engine for economy, ease of maintenance etc. there is virtually no choice but to have an inboard setup but if there was a diesel outboard that was no so heavy it would tip up the boat I am sure it would be a better option.

AVONMON · 23 January 2009, 12:23

Hi,I thought the main reason for having a diesel taking capital cost and fuel out of the equation was for reliability in the mairine environment ie no H.T system to worry about.There is a large l.p.g market for''petrol'' engines in Australia.There is plenty of ventilation in a R.I.B but I would not fancy it myself.

BogMonster · 25 January 2009, 01:19

One other thing I forgot to mention that would put me off is that possible petrol vapour in a sealed engine compartment on a petrol inboard would scare the sh&t out of me!!

It is probably an irrational fear but a fear all the same...

codprawn · 25 January 2009, 03:46

Quote:

Originally Posted by BogMonster

One other thing I forgot to mention that would put me off is that possible petrol vapour in a sealed engine compartment on a petrol inboard would scare the sh&t out of me!!

It is probably an irrational fear but a fear all the same...

Fully justified but that's what a bilge blower is for.

I remember once cleaning the distributor and alternator on my 110 V8 with trike cleaning spray. It was a cold day and indoors. I started the engine. There was a load pop and a flash from the alternator. It sounded exactly like a diode blowing.

Tried again and there was a hell of a bang. The dizzy cap had blown off even though it was properly secured with very strong clips. Put it back on and everything was fine but the forces must have been amazing.

Now I use a hairdryer to make sure it has all evaporated first.

r mcdonald · 20 February 2009, 11:33

Everyone
Thanks for the replies. The blokes across the road were I am building my Rib have given me an 175 johnson outboard, so I am going to see if I can get it going and stick it on the transom and see how it goes.This motor is not going to be on the rib forever. So when it comes to getting a new engine I think I will take the best deal at the time, as it doesn't seem to matter what you put on the rib, as long as you have enough power and the boat is balanced all types of engines have their pros and cons.
rpm

Matt · 20 February 2009, 13:41

Errr, no. That's what good rigging is for.
A vapour sensor & the blower are just extra proctection.

Quote:

Originally Posted by codprawn

Fully justified but that's what a bilge blower is for.

Matt · 20 February 2009, 13:53

I'm not sure I agree.

Show me a 600hp outboard?

In fact, show me a 600hp diesel motor that won't destroy a standard (ie bravo) drive.

It's actually a pair of universal joints, not the CV joints like mini's had.

Easier to access - well, if I were at sea and had a breakdown, I'd rather have my head in the engine bay to fix it than hangover over the back.

Cheaper to service - A service is oil filters, oil, plugs, impeller. The plugs for my opti are, IIRC, 30 quid a pop! The plugs for my old merc V8's were about a fiver. The fuel filters are exactly the same.

Reliable - Outboards suffer from the brackets being weak, it's very possible to break them regularly. Merc offshore ones were the strongest, and cookee still broke em regularly. Outboards won't survive a proper stuff, once water has gone down the inlet it's prob game over. An inboard has a much higher chance of surving a stuff. Diesel even more so than petrol.

Re shallow water beaching - each to their own, I wouldn't want my boat on the beach, or at risk from running aground. But if you are running a rescue boat, it's a fair comment.

Quote:

Originally Posted by TangoTango

Having had a cruiser with a petrol outdrive, I would say that if you are going to use a petrol engine, an outboard is far better than an inboard. They are easier to access, cheaper to service and as has been pointed out already they take up no space in the boat. The final nail in the coffin as far as I am concerned is that if you operate in shallow water, lifting up the leg of an outdrive is liable to cause you problems. Although theoretically they are able to be lifted nearly out of the water while running, in practice it can damage the universal joint (or whatever it is called, I think it is like the CV joint on an old Mini) or pull off the gaiters and let water into areas where it should not go.

If you decide on a diesel engine for economy, ease of maintenance etc. there is virtually no choice but to have an inboard setup but if there was a diesel outboard that was no so heavy it would tip up the boat I am sure it would be a better option.

TangoTango · 20 February 2009, 22:31

Quote:

Originally Posted by Matt

Cheaper to service - A service is oil filters, oil, plugs, impeller. The plugs for my opti are, IIRC, 30 quid a pop! The plugs for my old merc V8's were about a fiver. The fuel filters are exactly the same.

That sounds like cheaper to service if you do it all yourself and probably ignoring the time spent. I used to spend hundreds every year on outdrive servicing alone.

Quote:

Originally Posted by Matt

Re shallow water beaching - each to their own, I wouldn't want my boat on the beach, or at risk from running aground. But if you are running a rescue boat, it's a fair comment.

I wasn't talking about beaching. Try spending a season in Christchurch Harbour.