What Size Engine?

happyharvey · 24 September 2013, 22:29

We have been out in our Honwave T35 and are very impressed with it. Four up (2 adults/2 kids) with all our kit and a 20hp 2 stroke on the back it goes really well.

However it has dawned on me, if we decide to do a bit of river cruising this engine is going to be too much. It will spend all its time just above tickover straining at the leash!

The question is, how small can we go on the engine before we have problems going against currents?

I have no experience in this area and would welcome any comments.

Many thanks,

Harvey.

A1an · 24 September 2013, 22:35

Go for a 20hp four stroke?

It'll happily sit there all day on idle saying nowt and gently sipping away at your fuel.

I've got a Honwave with a Honda 20 on it, best of both worlds.

Landlockedpirate · 24 September 2013, 23:02

Quote:

Originally Posted by A1an

Go for a 20hp four stroke?

It'll happily sit there all day on idle saying nowt and gently sipping away at your fuel.

I've got a Honwave with a Honda 20 on it, best of both worlds.

Nooooooooooooooooooo. 4 strokes good, 2 strokes better

(On a lightweight sib

)

The OP doesnt say if its an Autolube engine, but IMHO with Yamaha's it really doesnt matter. Either autolube or running 100:1 it will be fine, if its a really old one on 33:1 or 50:1 then run it a little lean when you are on the river.

clydeoutboards · 25 September 2013, 06:31

Quote:

Originally Posted by Landlockedpirate

Nooooooooooooooooooo. 4 strokes good, 2 strokes better

(On a lightweight sib

)

The OP doesnt say if its an Autolube engine, but IMHO with Yamaha's it really doesnt matter. Either autolube or running 100:1 it will be fine, if its a really old one on 33:1 or 50:1 then run it a little lean when you are on the river.

sorry in this case I disagree., He has a great package and as A1an has said it will sip fuel and the OP knows the engine and that its reliable.

so why would the OP want to spend more money on a 2nd engine that he does not know, have another service cost, storage, etc. also the op is not looking for speed or acceleration and is just looking to potter around which again is another + for his current set up.

Dave

Sunstreaker · 25 September 2013, 14:19

Interesting question. If costs and storage were not a problem to the OP, what would people's advice be. 5hp four stroke, any higher or lower suggestions?

The Gurnard · 25 September 2013, 17:02

Quote:

Originally Posted by Sunstreaker

Interesting question. If costs and storage were not a problem to the OP, what would people's advice be. 5hp four stroke, any higher or lower suggestions?

I realise everyone has different ideas, but personally I would not dream of going to sea without a back up engine. My main engine is very reliable..but things like starter cords can snap or the prop can hit submerged objects rendering the outboard engine unusable.

This SIB is 4.3 meters long and the 3.3Hp 2 stroke will happy push it along at displacement speeds of around 4 or 5 knots.

I dont know what strength of currents that happyharry is referring to in the river..but if they are strong currents..then I would use the 20 HP in those and switch to a small back up engine when happily plodding along in the deeper quieter parts of the river. Its far easier on the ears too.

A small second hand auxilliary engine can be picked up quite cheaply and certainly gives me piece of mind having two on the boat. I consider myself lucky as I have two x 2strokes on the back of this SIB and they probably have a combined weight of less that one modern four stroke main engine.

henryfreston · 25 September 2013, 17:05

Quote:

Originally Posted by The Gurnard

I realise everyone has different ideas, but personally I would not dream of going to sea without a back up engine. My main engine is very reliable..but things like starter cords can snap or the prop can hit submerged objects rendering the outboard engine unusable.

This SIB is 4.3 meters long and the 3.3Hp 2 stroke will happy push it along at displacement speeds of around 4 or 5 knots.

I dont know what strength of currents that happyharry is referring to in the river..but if they are strong currents..then I would use the 20 HP in those and switch to a small back up engine when happily plodding along in the deeper quieter parts of the river. Its far easier on the ears too.

A small second hand auxilliary engine can be picked up quite cheaply and certainly gives me piece of mind having two on the boat. I consider myself lucky as I have two x 2strokes on the back of this SIB and they probably have a combined weight of less that one modern four stroke main engine.

I disagree. a 4hp 4 stroke is much louder at idle than a 20hp 4 stroke...as soon as you hit 2 cylinders the noise reduces lots.

The Gurnard · 25 September 2013, 17:15

I guess I need to get my hearing checked then Henry.. the 3.3 is a single cylinder and the 25 is two cylinders and its certainly easier on my ears..perhaps I have a hole in the exhaust of the 25 HP ?

My tohatsu 4hp four stroke also seems noiser to my ears that the wee 3.3 two stroke..but I dont rev the guts out of them

henryfreston · 25 September 2013, 17:22

Quote:

Originally Posted by The Gurnard

I guess I need to get my hearing checked then Henry.. the 3.3 is a single cylinder and the 25 is two cylinders and its certainly easier on my ears..perhaps I have a hole in the exhaust of the 25 HP ?

My tohatsu 4hp four stroke also seems noiser to my ears that the wee 3.3 two stroke..but I dont rev the guts out of them

I don't know if it different with 4 strokes but the the smaller 4 strokes tend to be quite noisy

Dinghy and Mercury 2.5 hp fourstroke in Langstone harbour - YouTube

Mercury 20 hp 4-stroke 2012 mod - YouTube

henryfreston · 25 September 2013, 17:23

Oh damn, just realized that the OP has a 2 and not a 4 stroke, my bad!!

happyharvey · 25 September 2013, 22:12

Thanks for the input guys. Not surprisingly there is no right or wrong answer to my question but reading between the lines I think we can agree on the following.

Running the 20hp outboard just above tickover will not compromise its performance or reliability. (I do think it compares to using a Ferrari to to do the weekly food shop though).

A 3hp outboard should be capable of displacement speeds in favourable conditions.

Just to clarify my present outboard is a Autolube Yamaha 2 stroke which is not particularily light at about 50kg.

Harvey.

Sunstreaker · 27 September 2013, 22:02

My understanding is its reliability could be compromised.plugs more likely to oil up.

clydeoutboards · 28 September 2013, 06:27

Hi

having just come back from the largest free fishing event in the uk ( and going back today and tomorrow) they like the Nissan engines with which ever badge is the cheapest i.e. mariner , mercury, Tohatsu. 3.5-6hp. 4 strokes.

Dave

Brendan Townsend · 28 September 2013, 13:36

Potential for plug oiling is a fair point with 2-strokes when run near tickover for extended periods. I believe they prefer to run hard, with the accompanying noise. I usually ran my old Evinrude 4 2s around half-throttle so can't add anything more.

I bought our Tohatsu 15 4s for quieter long river trips, with the clout to cover occasional coastal use. It's lovely and quiet and I couldn't be happier with my decision, despite the substantial extra weight.

Brendan