What engine

[alanch]

Now that my river boat is sold, I am considering the purchase of a Merry Fisher 650 (other boats are available)! The question is inboard diesel or petrol outboard of about 100hp.
I have heard all the arguments re cost, fuel availability, range, noise etc, but what this post is about is wear and tear and reliability of said engines with the following usage in mind.
My preference is to keep it on a non tidal river, speed limit 5kts, used for short journeys, with the occasional blast out to the estuary. So what engine is best for that? If that scenario was reversed to being kept on the estuary with the occasional foray to the non tidal, would that change engine choice? What does the forum think?

 

[rafiki_]

With your usage, I would suggest the outboard. Cheaper to purchase and service, and you can tip it up out of the water when not in use. Fuel consumption will be higher but easily offset by other costs.

 

[Bouba]

Are you buying new? There is nothing more reliable than a modern outboard especially Japanese and especially Honda

 

[Oscar24]

OB all the way.
I have a MF 645 with a Suzuki 115 and love it!
It's good for 25kts but is just as happy sitting at 6kts.
Unless you intend to do 100s of hours motoring a year, then petrol is IMHO the way to go. At 6kts you can hardly hear the engine.

 

[Seastoke]

Outboard all day if the diesel was on a leg service is massive and sitting in water all its life if shaft u have to watch you depth

 

[alanch]

Thanks for your replies so far. It will not be new and if diesel inboard I would only have a shaft drive. Probably no more than 100 hours a year if that. It seems that OB is the forums choice so far.

 

[Momac]

It would take a lot to tempt me to a petrol engined boat - but the smaller the boat the more petrol is worth considering . Even if the petrol engine fails it would cost a lot less to replace than a diesel.

.

 

[QBhoy]

From the use you have described, I'd say the petrol outboard.
Counter would be that having a diesel shaft drive is always appealing. Be more costly to buy though.
Diesel wouldn't be terribly happy overall at low speed for the most part. They like to be worked hard.
The outboard would be almost as economical these days and happy plodding, flat out and anything in between.

 

[Jim@sea]

With your usage, I would suggest the outboard. Cheaper to purchase and service, and you can tip it up out of the water when not in use. Fuel consumption will be higher but easily offset by other costs.

And easier to remove by thieves

 

[QBhoy]

Very true Jim !

 

[oldgit]

Diesel wouldn't be terribly happy overall at low speed for the most part. They like to be worked hard. .

Not sure this is any longer strictly true.
Especially in the this class of small very efficient lightwight high output diesels.
The days of enormous super heavyweight old plodders needing a week to get up to temperature and running at low revs most of the time has long gone.
Most now are based on automotive blocks ? which have to cope with short to the shops trips which barely get the oil warm,yet how often do you hear complaints of bore glazing in any micro car shopping diesel. ?
Also non tidal rivers are chock a block with low use short trip diesels, how often is an engine written off, never ?

 

[simonfraser]

5 kts ?

25Hp should do the job ?

 

[alanch]

And easier to remove by thieves

Yes, that does concern me. Trying to find if much of that goes on on the Mudway.

 

[alanch]

5 kts ?

25Hp should do the job ?

Unfortunately you will not find a MF 650 or similar with much less than 90hp. Could always sell it and get a new 25hp. But that does not meet my idea of blast down the estuary!

 

[oldgit]

If boat was going to live on trailor,then O/B would make sense.
However assuming this is going to be moored afloat at Allington ? marina then a less convincing case for O/B.
Hit the rocky bottom with O/B prop and its a ruined day,most of the inboard small fishers have a sked protecting the propeller.
If you are going to moor above lock,suspect you are going to go stir crazy after a few months lock hopping ( ask any long term Thames boater) and its a long way and two lock transits to get out to the estuary for a days fishing, basically you cannot do it.
Far better to be based tidal,with 24 H access to to outside world whenever you feel like it.
Any above the lock trips can be planned over few days or weekend and no rush to get back to lock on same day.
There are at least couple of this type of boat which I know make regular trips upstream and they can get to Yalding at the very least.
Both are diesel on shaft..

Do happen to know of club with very reasonably priced moorings, a very active cruising and social scene located in just the right spot,unfortunately a rather long mooring waiting list,but club members who moor away do get some free overnight moorings.
Also very useful for overnight accomodation when attending any the festivals and other attractions in the Medway area.http://www.enjoymedway.org/events/search?event-category=6&area=All

They do have several members who moor at Yalding /East Farleigh and Allington who take advantage of this.

 

[wipe_out]

From a fuel cost perspective at 5kn there probably isn't much in it.. My suggestion is go and see all options in either format and find the boat you like, the one that looks well looked after and feels right for the money..

 

[oldgit]

From a fuel cost perspective at 5kn there probably isn't much in it.. My suggestion is go and see all options in either format and find the boat you like, the one that looks well looked after and feels right for the money..

+1

 

[NormanB]

A useage pattern of 5 knots for the majority of the time would lend itself to electric drive - combined with solar could be a green (ish) solution. You do not need much power to do 5 knots ( well not much compared to 20 knots) Of course it would fail miserably on the estuarine bashes.

 

[oldgit]

A useage pattern of 5 knots for the majority of the time would lend itself to electric drive - combined with solar could be a green (ish) solution. You do not need much power to do 5 knots ( well not much compared to 20 knots) Of course it would fail miserably on the estuarine bashes.

There is on the Thames (where else) a electric boaters club.

 

[Bouba]

There is on the Thames (where else) a electric boaters club.

Electric boats were obsolete technology by the time of the First World War. Perhaps it'll make a comeback one day