Disadvantages of petrol (inboard)

[l'escargot]

Petrol is dearer than marine diesel.
Petrol is not as widely available in marinas.
Petrol engines are more prone to starting problems if damp because of electrics.
This is in addition to the greater perceived risk of flammability.

For these reasons:

Boats with petrol engines are generally cheaper than the same boat with diesels.
You will find that people will remove petrol engines and replace them with diesels but not the reverse.
The majority of new boats have diesel engines as standard.

 

[Judders]

Its another GK24. The engine is a Vire 2hp 2//.


It seems to me a reason to negotiate the price. Would it be best replaced with an diesel inboard of shall I treat myself to a big locker and an outboard bracket?

What do new/second hand diesels cost and how much are they to install?

 

[l'escargot]

Vire - some love em, most hate em.

New diesel allow 4k to 5k, you will never recoup the cost but if you plan to keep the boat some years you will get the use to justify it. You can sometimes pick up reasonable second hand diesels for 1/2k to 1k, but I don't think there are any diesels that fit the Vire footprint so you would need substantial mods to the engine bearers and shaft etc. which is a professional job and costly. Personally, I would go for the outboard option.

Info on the Vire here with some links, notoriously unreliable and spares are becoming hard to get although there is someone Christchurch way (I think) who still rebuilds/reconditions them. Saying that, I know an old boy in his eighties who still has one that he put in new in a boat he built himself and he swears by it.

 

[SeadogUSA]

Defintely a euro thng. Most boats in the U.S. are gasoline powered. Only the biggest boats have diesels and a lot of inland marinas do not carry diesel. There rarely any problem and most are due to owner incompetence. Proper blower use and maintenance is a must. Marina operators are usually very dilligence about making sure the owners follow safety procedures.

 

[BrendanS]

I've given up on them years ago. Myself and others have pointed out in thread after thread that USA has more petrol boats the all of Europe put together, and given it's coastguard statistics and the fact that the USA is one of the most litigious countries in the world, Petrol boating cannot be that unsafe, if they keep putting petrol engines in boats. I own a petrol boat, and blowing up due to petrol is usually the least of my worries

Doesn't really matter though, as we have a huge number of people who are emotionally attached to the fact that their diesel engine is safer, and no number of facts from the real world will change their mind.

 

[Ships_Cat]

I think there are probably two backgrounds that people come from on this and which is a cause of differing views.

Putting or having a petrol engine in the bowels of a saily yacht is just plain dangerous in my view (and I know the industries too - never see it done) - and probably the same for deeper canoe drafted displacement MoBo's. So saily types tend to be opposed.

Whereas for those used to smaller MoBos (which tend to be more open) having greater airflows through the engine compartment (often force vented during engine run, or for pre-start) petrol is not regarded as nearly as much of a problem and I tend to agree for small vessels.

But in saying that when providing safety management services to commercial vessels (including statutory surveys with around 35 surveyors) we would not touch petrol powered passenger vessels, because of the risk, except in special circumstances such as in smaller adventure type boats requiring high performance eg jet boats, normally around 18 foot, giving thrill rides up heavy river rapids with very heavy passenger loads and required to accelerate from whoa to cruise very quickly.

Personally, I would not touch petrol in a MoBo unless the boat is under around 6-7 m and so able to be stern driven (legs/water jets) with engine in box at transom at rear of cockpit with no bilge and force vented, or outboards. So, never with the engines within the boat's compartments at all.

As far as saily boats are concerned, wouldn't even get on a petrol powered one unless very small and outboard powered from a portable tank not able to drain into the bilge.

John

 

[BrendanS]

That would be fair enough, except those under 6-7m petrol mobos also potter around at idling speed for hours in the speed restricted areas with no problems at all. The stats say they aren't dangerous, the people that use them (sensibly) say they aren't dangerous. You can have fires just as easily in a boat with no engine at all, if the wiring is at fault, and most fires I've seen have started with wiring or exhaust problems.

 

[Ships_Cat]

Certainly in NZ the most common cause of fire aboard smaller power boats is caused by petrol vapour - these boats also generally have very simple electrical systems and what there are are of very light loads and energy so is not much of an issue fire wise (what I mean there is if one shorts the pos and neg of your average plotter supply you would be lucky to get more than a few sparks, but short a big alternator output cables to remote batteries or windlass cables on a larger boat with also alot more energy stored behind the fault and you get real fireworks).

For larger boats becomes electrical and things such as oil spraying onto hot turbos, etc but very few (probably none in those sizes) boats here are petrol powered anyway so would not expect petrol to show. However, even so, around mid '90's (if I recall the date correctly) Maritime NZ put out an Operational Notice - Boats claiming that petrol was the foremost cause of fires on launch's and set out the precautions to be taken. With the recent revamp of the Maritime NZ site these Notices don't seem to be available anymore.

I don't see any reason why NZ should be much different to other places as far as the risk to individual boats is concerend? Also, I personally don't know of any MoBo's over 7 or so meters now built here that are inboard petrol powered (but no doubt some).

For UK the document at http://www.waterways.org.uk/Seeing%20Red%20Final%20Version%20July.pdf claims:

Research conducted by the RYA (1998) has demonstrated that a petrol-powered vessel is more than 3.7 times as likely to suffer a fire as a diesel-powered vessel.

Perhaps we just have to agree to differ for a change /forums/images/graemlins/smile.gif?

John

 

[BrendanS]

No, I'd like to see the documents for NZ that the most common fire problem on boats in NZ is petrol vapour. It's certainly not borne out by stats in US who have a much bigger petrol based usage. Perhaps NZ users are particularly inept?

 

[Ships_Cat]

I'd like to see the documents for NZ that the most common fire problem on boats in NZ is petrol vapour.

Note I said smaller boats not all boats.

I have found a link to the NZ Boat Notice I mentioned and is http://www.maritimenz.govt.nz/publications/boat_notices/bn_021995.pdf. It refers to "launches".

I don't have any other NZ statistics which differentiate between the cause of fire apart from the reference to the Boat Notice I mentioned, but I would be very hard pressed to recall any fire on a boat under 6-7 meters or so that had a fire for any reason other than petrol. There just is not often anything else on board that can cause one (if gas for cooking it is usually portable or in open spaces and no bilges to collect in, etc).

For USA the statistics for 2004 ex USCG are at http://www.uscgboating.org/statistics/Boating_Statistics_2004.pdf. If one compares in the table on page 36 (the pdf page not the actual page number) the numbers of fires from "Fire or Explosion (Fuel)" to "Fire and Explosion (Other)" one can see that the fuel one is a number of times greater. Similarly on page 37 looking at "Fire and Explosion (Fuel)" one can see that for boats in the 15 - 24 foot range (ie those most likely to be petrol powered) that is also the pattern but once you get to bigger boats (presumably much more likely to be diesel powered) then the difference between the "Fuel" and "Other" causes is no longer apparent (similarly for boats under 15 foot also where likely to be outboard if powered).

The reason the statistics for all USA boats is not greatly different to the 15-24 foot ones even though fewer such fires on bigger boats is that boats in that smaller size range comprise the majority of boats (typically in western countries around 90% or more of boats are under 7 m).

The USA statistics are for all vessels so including sail, where would be unusual to be petrol powered, non the less fuel fires show up as around 3 to 3.5 times as likely to be cause of fire than non fuel, and that in the boat size range where one would expect the fuel to be predominantly petrol in USA - which infers petrol is a bigger risk than diesel as bigger boats have much fewer fuel related fires. That figure is also in the realms of the 3.7x figure in the UK document I gave the link for.

Interesting to see the risk from fire compared to other risks and I suspect that is so in most places. Here, the accident numbers due to fire are very small in comparison to all others (all though probably more catastrophic than many).

John

 

[SeadogUSA]

The stats show that fire is a very insignificant problem on boats in the U.S. The big problem is PWCs operated by idiots, and drunks on boats. Also, a large percentage of sail boats have kickers, so they have many of the same concerns.

A diesel engine in the states will cost at least $10,000 over the cost of a gas engine of similar power. And diesel is often more expensive than gasoline. Very few boats under 10m on inland water will use diesel engines. The most popular engine for I/O applications is probably the 4.3L GM V-6, followed by the 5.7L V-8. If I was going to have a large cruiser and money was not a factor, I would prefer diesels. However, here, gasoline rules. We tow our boats to the lake, stop at a gas station on the way, and fill the tank. Those who keep their boats in slips on the lake are faced with a 25-50% surcharge for buying on the water. I do not claim any knowledge about the way coastal boats are operated. Their numbers may be different, but only on the bigger boats, I suspect.

 

[Ships_Cat]

Yes I agree, fire is a low risk compared to the other things, hence the last comment in my post - that is shown in the USCG statistics and is also the case here in NZ.

Similarly here, trailered boats are virtually all (probably all?) petrol fueled.

I suspect it would be very difficult to get petrol in a marina here - I have never seen it in fact, but there again never been looking for it either, but certainly the few marinas I frequent just do not have it.

{Nice time of the day this, no Brits around to cause trouble /forums/images/graemlins/smile.gif}

Regards

John

 

[bumblefish]

Oh yes there are, just some of us don't know the answers and are content to follow other's advice.

 

[PowerSlapper]

Me too, I'm here but cannot be bothered with the same old arguements about petrol on board. I don't carry any petrol on board except for my trusty Zippo. Nothing but red for the boat and bottle or three of "white" for me.

Jules.

 

[Slow_boat]

In the summer of '76 my brother and young girlfriend were in Cowes marina filling up the Folkboat tank with petrol. There was a leak in the tube from filler to tank, resulting in fuel spilling into bilge. In that very hot summer this vapourised quickly so that when girlfriend lent into the cabin to start the engine and a faulty connection caused a spark she got blown clean over the stern and the only bits not burned were under her bikini. She died. He was in hospital for two years and still bears the scars, both phsicaly and mentally.

That put me off petrol inboards.

 

[Lakesailor]

That's frightening. I have a fuel can for my outboard. On small yachts much less consideration is given to venting the fuel vapours. Even if you keep the can in the cockpit the vapours still sink to the bilge.
How long do they remain flammable and how much vapour is risky?

 

[Twister_Ken]

Hardly matters for pottering, but diesel is also more 'energy rich'. Therefore a given volume of diesel will take you further than an equivalent volume of petrol. Matters for ocean crossing, I guess.

Also, diesel only needs air and fuel to run, petrol also needs electricity for sparks. Electricty and seawater are not good friends, so maintenance probably more important with petrol, plus extra complication of bilge blowers, etc.

 

[Slow_boat]

I carry a petrol tank for the outboard in a cockpit locker that is vented overboard and has no way into the bilge.

When you fill a can for the outboard, you're doing it in the open air, probably not even on the boat, so you're not going to get petrol in the bilge. Never fill where you can't spot and deal with spillages/leaks. Any smell of petrol in the boat means petrol vapour so needs investigating and sorting. No naked lights until it's traced and sorted, either.

Starting the outboard is also in the open air, so no vapour around should there be a stray spark.

As to how long it takes to become explosive and how long it stays that way, I guess that depends on air temperature, wind etc.

The summer of '76 was very hot, the day very still. We were young and not particularly safety concious and his girlfriend hadn't much experience, so wouldn't have recognised the danger even if she recognised the smell.

A hard way to learn, though.

 

[Mirelle]

You will hardly need the engine.

A GK 24 will actually SAIL, and is a size that is easy to handle.

I'd buy a Seagull Century and keep it in the locker. You will very seldom need it.

The reasons for recommending a Seagull are these:

1. Cheap.

2. Stands neglect (in bottom of locker!) better than modern engines.

The space that you will gain by dumping the Vire, and the reduction in propeller drag under way, will more than compensate.

I would be cautious about buying a secondhand small diesel. They tend to be Japanese, and spares come from the Land of the Rising Yen. Don't ask me how I know that - well, OK, I bought a Yanmar 1GM 10 for £1,000 and spent rather more than that on starter, alternator, water pump...

 

[Ships_Cat]

how much vapour is risky

Roughly same (actually a bit less) as LPG which is generally taken as 2-10% - so not much needed at all.

We do all the same things as DuncanHB2, including the ventilated locker (is actually exactly the same as the gas locker) which has a big rectangular exit vent flush with bottom of the locker which goes straight out thru the transom so liquid cannot pool if containers leak.

John