Thread: Petrol or Diesel for boats

My biggest fear of a petrol powered boat is fuel leaking into the bilge and vaporising you go to start the boat and it goes of with a real bang, diesel if it leaks is not going to form a vapor in the same manner as petrol but given your talking about a petrol outboard it's less of a concern.

I still like diesel but it doesn't sound like the boat is big enough to justifiy the weight and size of an inboard diesel


Cheers
Rob

Same view as Rob. Petrol in boats can be very dangerous (vapour is heavier than air and collects in bilges waiting for a spark!), but in small open boats the risk is low if care is taken. Diesels are generally much more economical to run than petrol engines, but again, with a small boat the difference is unlikely to be enough to justify the extra cost and weght of a diesel.

John

Depnds on the type of hull. Displacement hull runs long hours at say< 10 knots then diesel's the go. Planing hull runs in short bursts at say >20 knots then petrol outboard is the go. Horses for courses, depends on hull design and application.

Deano

how big is the boat? how much preventetive maintenance will be done? I have seen 2 petrol boats explode, both causing injury. Personally I'd go diesal

Diesel for inboard,I have seen a big boat explode,luckily with only minor injuries to those on board.
Look at Yanmar diesel.They do a very good 6cyl with HEAPS of power,it is infact a copy of the Landcruiser HZJ motor,marinised with MUCH more power than toyota ever got out of it!!!!!! VERY economical in a boat Im told.
Andrew

Thanks for all the pointers, I'll pass them on to my mate.

Petrol outboards seem pretty popular, so they can't be all that bad?

Being a smoker, I quized about the pro's and con's of a fire hazard aboard a 35' cruiser we hired for a week,, I had several people tell me there are more fires in desiel boats than petrol, including my dad who was navy,, people get careless thinking the deisel is safer apparently,, I've never seen any facts to back up those therories though,,
And I must say, cruising around for the week cost us next to nothing,, didn't smell anything either. The 5.5mt and my small tinnie, I've owned and own, all you could smell was fuel,, not much in the big one, probably only exhaust,, but in the 2 stroke,, crap,, makes it sickening sometimes,,

Marine propulsion is taking a similar line as to 4wd propulsion just a few years delayed.
The advent of small, light, relatively high reving, electronic diesels is making inroads into the smaller boat market. 10 years ago a 21-22 footer with dieso donk stern drive would be pretty uncommon. With fuel price increases and the newer diesels coming online the game is changing.

I have not come across the FNM diesos so my comments below are more generic than specific.

-First, dont be too scared of petrol power - there are thousands of outboard powered 21 footers that have not and will not blow up! Risks are everywhere.

-Second probably need to establish the type of hull boat? I will assume it is a true planing hull. If it is semi-displacement then no choice hands down dieso all the way.

-The dieso will have more torque and throw a bigger prop/ props and combined with its calorific benefits give better fuel economy if at a lower top end speed.

-There is minimal difference in weight between the FNM and my guessed at other option.

FNM 240kg
bravo3 stern drive 68kg

yam4stroke 200HP 270kg

-The dieso will have much better weight distribution, assuming the hull has been designed for it.

-Sooooo, that would make the most logical decision to be based on upfront and running costs. What sorta distances do you travel, do you need long range cruising. What sort of distances does your mate cruise... longer distances and more time available will tip to the dieso.

-Finally and some might argue more importantly on the troll diesos will raise more fish than petrols!

S