Outboard vs Diesel Inboard

[Bear]

Hi All

Is there a preference for either outboards or inboard diesels?
Is there anything to look for on either style that is of concern?

Thank you

Bear

[Phillip]

Diesel Inboards [DI] are quieter than Petrol Outboards [PO]

DI are more fuel efficient [my 10hp D Nanni uses .9 litres per hour] [PO depends on size 2 or 4 stroke, someone will tell us how much]

DI cost more to buy and maintain.

PO don't last as long.

PO are smelly with fumes.

PO require a lot of petrol onboard

DI take up a lot more room down below.

DI have alternators to charge batteries which is not always the case with PO.

DI have a larger propeller which drives boat better than a PO

DI have the prop ahead of the rudder which means more move-ability

Both DI and PO have cruised around Aust and overseas.

PO are a security concern.

Look what ever a Top Hat has when you go to buy it, if you love the boat and it feels comfortable and it seems to be you, go with whatever motor it has!

[Miker]

Diesel Inboards [DI] are quieter than Petrol Outboards [PO]

DI are more fuel efficient [my 10hp D Nanni uses .9 litres per hour] [PO depends on size 2 or 4 stroke, someone will tell us how much]
.... snipp

Look what ever a Top Hat has when you go to buy it, if you love the boat and it feels comfortable and it seems to be you, go with whatever motor it has!

That's the opinion of a guy who's got a lot of sea miles with a diesel. Probably more than anyone else on this forum. All very salient points, and very well put Phil.

I'm in the outboard camp. I have one, and it's been brilliant. The difference is, that it's not in the well. It's over the back on a lifting bracket. It's locked in place for security. So much so that I need bolt cutters to get it off. It's not pretty back there, but it is functional, and more quiet. Oh, and if you need to, you can steer the boat with the outboard, instead of the tiller. Providing it's on the stern and not in the well. I can turn in almost my own length. I can also steer in reverse, which is almost impossible with an inboard.

It can be serviced in place, if on a calm day, or on the slip. OR, you can take it home at your leisure.

Mine is a 8hp 4 stroke Tohatsu with a 4 blade hi torque prop. Gets 6 knots in calm water. No charging system, but it's available. No electric starter, but it's available. However, it's simple and reasonably quiet in the back. Much quieter and less smelly than a two stroke, but not as light as a two stroke.

Drawback for me, is that the shaft is standard, so it will lift the prop out in short choppy conditions, but only if there's too much weight up front. I've been in and out of Swansea channel a couple of times, with no problem. I go into and out of Brisbane water, whatever the tide, with no problems.

It uses approximately 1.5 litres per hour at 3/4 throttle, which is plenty and with my 30 litre fuel tank that's 20 hours of motoring. I also have a 9 litre spare drum.

It's a 2003 model, and never gets rinsed with fresh water, unless I take it home for it's annual service. The built in anodes take care of corrosion internally and the Lanox takes care of the business under the cowling. Even after 3 months of no use, it will usually start on the 2nd or 3rd pull of the cord. Simple, no nonsense. No shaft leaks through the hull, no bearings, no oil leaks into the bilge. A Top Hat has been around the world with an outboard, so they can't be that bad.

However, as Phil says. Don't let the engine type put you off the purchase, if the boat feels right to you, and it looks like it's been reasonably well kept and looked after, then go for it. There is very little can go wrong, providing the maintenance is kept up.

With this topic, there are and have always been, pros and cons for both sides of the camp. Enjoy your hunt!

[steve]

Don't be put off by an outboard in a well. Provided that the outboard is not so large that it can not be turned within the well, it will provide excellent steering in both forward and reverse. An inboard makes steering in reverse almost impossible. The lack of steering in reverse will probably not be a problem if you keep the boat on a swing mooring with plenty of space around it, but if you are in a marina or on a mooring in a channel then the ability to steer in reverse is very useful.

If I was buying a brand new boat I would have an inboard and a bow thruster. If buying an old boat, an outboard in a well has a lot to recommend it, particularly if it has an ultra long shaft and a high thrust prop. Old inboards with old tanks, shaft seals, engine mounts, filters and all the other paraphernalia required by inboard diesels can be very time consuming and costly.

[Phillip]

Going astern.

No matter whether you have an outboard or an inboard, going astern is always something you must plan NOT to do unless its an urgent stop.

Unfortunately Top Hats in reverse are going the wrong way and I always try and avoid that situation as much as possible.

Most common situation is coming out of a marina berth and even there its in and out of reverse gear just enough to get her moving. before going into forward gear!

Don't stress over it, all Top Hats are the same

[Bear]

Thank you for all your replies. Gives me more to think about

[Swift]

I finally got around to selling my Mercury 2003 6HP 2 stroke just before Christmas. It was still starting first pull and ran as well as ever but you know, all those years salt water use without flushing? How long do these things last? A bloody long time but not forever so for a bit of insurance it had to go. The motor was about $1700 in 2003 and I sold it for $300 so the costs of purchase over 16 years was less than $90 per year. Maintenance was simple and costs next petty change, a new impeller and 2 new spark plugs every two years. That's it

For me, low costs, simple servicing and ultra reliability far outweigh the lower cost of diesel fuel. Diesels are quieter but there's other potential complications I can live without: prop drag, prop fouling, stern gland things, drive shafts, wet bilges, heat exchangers, engine mounts, oily bilges, smells in the cabin, less storage room etc

I replaced the motor with a 10hp Tohastsu (same as Mercury), it's a 2 stroke, one of the last ones to be imported into this country. As well as being more powerful it's a bit quiter than the 6. I'm extremely pleased and will be absolutely delighted if I am still around and still sailing when this motor is due for replacement.

[lockie]

Horses for courses: diesel for extended cruising, OB for day sails and short cruises.

The difficulty in safely carrying enough highly-flammable fuel for long passages would be a huge deal-breaker for me. It can be done, just adds more hassle and safety issues. Fuel fire on a small yacht way out on the oggin? No thanks.

Steve's comments about maintenance certainly have merit and reflect my experience. You have to be an insane masochist to deal with an older diesel, but that's why we buy old yachts in the first place.

Cheers Graeme

[Miker]

Horses for courses: diesel for extended cruising, OB for day sails and short cruises.

The difficulty in safely carrying enough highly-flammable fuel for long passages would be a huge deal-breaker for me. It can be done, just adds more hassle and safety issues. Fuel fire on a small yacht way out on the oggin? No thanks.

Steve's comments about maintenance certainly have merit and reflect my experience. You have to be an insane masochist to deal with an older diesel, but that's why we buy old yachts in the first place.

Cheers Graeme

https://www.paintandpanel.com.au/articl ... 61E4B25B23

Jamie Mitchell sailed the world with his Top Hat, and an outboard.
Of course, I get the danger of fuel fires, I've had one from a stupid mistake on a metho stove. But - diesel is almost as flammable, and apart from an alternator or battery spark or a naked flame from another source, there is nothing to ignite the petrol. It's why we take special care to make sure there is no issue going to cause a spark and no petrol fumes present if we need to light the stove. It's the same as taking care to make sure the sea cocks for the diesel inboard are secure, the possibility of losing the propshaft is mitigated, and any other potentially dangerous failures are prevented before they cause a fire, or worse, a sinking..... let's not even talk about a gas stove/fridge set up

[lockie]

Mike;

I must respectfully disagree with your comment about the relative flammability of petrol and diesel. Petrol has a much lower flashpoint (around -40C) meaning that at ambient temperature it readily evaporates, causing vapours that can easily ignite from even a tiny arc such as in a 12VDC switch. Explosions on petrol-fuelled boats are far from unknown (https://transportsafety.vic.gov.au/mari ... refuelling).

Diesel has a flashpoint of about +60C, so at ambient the quantity of vapour is miniscule and not ignitable. The biggest risk is from an aerosol spray from a minute high pressure leak contacting a very hot (exhaust) surface.

Cheers, Graeme