Outboard Engine Big Enough?

[IzzyDD]

Hi All, I am looking at possibly purchasing a boat from a friend.  I am aware of most of the things I need to be considering in regard to this (safety certificates, hull blacking, etc) but one thing I am concerned about is the size of it's outboard motor.  It is a 27' Springer narrowboat and is powered by an 8hp Honda outboard.  It is currently only used on short stretches of the Rivers Ure, and Ouse north of York.  The engine is felt satisfactory for this, but not for trips South of York.  Can anybody provide me with any thoughts regarding this please.  In general I might have preferred in-board engine but I have good reasons for considering this boat.  Many thanks,  Izzy

[Tom Morgan]

I'm not an expert, but 8hp seems a little underpowered for such a heavy boat on a river.  (I say "heavy" by comparison to my GRP 23-footer, which has a Honda 9.9hp outboard on the canals).  The max speed I've ever got on a really wide bit of canal one day, was 7 mph.  I would worry about taking it on a river.  

 

Edited July 6, 2020 by Tom Morgan
Correct a spelling mistake.

[Alan de Enfield]

Its an 'OK' engine for Canals and 'mild' rivers, but I'd not be happy with an 8HP on rivers with any flow.

 

Just think - the 'normal' OB for small canal boats is 9.9hp and that's 25% bigger than the engine you are looking at.

Pretty much all OBs will get a boat moving (eventually) but the problem comes in when you are going against the flow and still going backwards.

Its not all about power, - you could quite happily use a 8 or 9hp inboard, but you'd probably have a 20" propeller on the shaft - with a little OB you'll have a 6" propeller.

 

I'd say NO !

[IzzyDD]

Thank you both.  

[Murflynn]

you may also like to consider that some larger outboards have a modest charging facility that does more than just recharging the starter battery.

[magnetman]

Honda 8 is a good unit. Not sure if it's a modern round box one or the older square type. Some of them had 4 blade high thrust props. If it's one of those I reckon it's ok if you are not intending to use it in arduous conditions. 

I've been on a 14ft boat with a Honda 8 with the 4 leaf clover prop and it was quite happy to push a 70ft narrow boat tied alongside up the Thames during yellow boards conditions. 

 

 

Not for a long distance maybe half a mile but it did get the job done. 

 

It depends how you like to handle a boat. If you want to be able to reverse and stop it dead then you need a 20hp Honda but if you just tend to glide around and take it easy I reckon the 8 is ok. It is technically too small but...

 

 

 

Edited July 6, 2020 by magnetman