Honda 2.3 HP Outboard

[David]

For those that may be interested while waiting for the afternoon sea breeze to pick up I decided to see what the range was for the new 2.3HP Honda outboard that came with my BR20.

On one tank of fuel (1 litre) I got 6.7nm at an average speed of 4.5 knots, which is not flat out, top speed is around 5.5knots. This was in calm water with 2 people and not much extra gear apart from anchor and chain.

Cheers
David
Little Ripple
Australia

[Craic]

Hi David,
well done.
So the fuel efficiency of the Honda 2.3 is quite similar to that of the Suzuki 2.5,  http://www.swallowboats.co.uk/component/option,com_smf/Itemid,52/expv,0/topic,248.0 .
A can of 5 ltr. petrol i.e. in money GBP 6.70 will keep you going under motor for around 35 nautical miles, for me that is what I motor in total over several months. It is ridiculously cheap. Going to the movies -just once- is more expensive.

[Julian Swindell]

I used the Honda 2.3 on my BayCruiser for the first few months. Power wise it could cope with just about anything, but where I sail (Poole Harbour) I often get caught by strong headwinds and very strong head tidal currents (often up to 4 kts) That meant getting back to the mooring very late on several ocassions, so I decided to invest in a Tohatsu 6HP. That has coped with everything very well, even getting through the Hurst Point narrows against a full strength foul current. It took over an hour to cover half a mile, but after that we could head straight home. We would have had to wait another four hours for the current to change,which would have nmeant getting home in the dark.
The downside is that it is heavier and takes up much more space in the cockpit when tilted. Economically I haven't checked it, but running at low power it cruises at 4kts and seems to use very little fuel.
The two things I really didn't like on the Honda is that it is very noisy and doesn't have reverse. I work in and out of pontoons and marinas quite often, and lack of reverse can make that a bit of a challenge.

[Craic]

Julian,
your boat is much bigger than a BR. And then I remember you do not empty your tank.
In our Raiders we have not come across a headcurrent anywhere which our small engine was not capable of pushing us through. The key is to keep out of the main current and go through the extreme shallows like a native. In the Morbihan in one main channel the nominal current runs with -famously- 10 knots. Near the rocks on each side that goes down to just 3 even in the worst places at the worst of tides. And as for negotiating strong headwinds, that is what the Raiders have the Gunter rig with the short main mast for, which can be taken down or stepped in a jiffy while at sea. I think you cannot do that in your boat with it's long mast.

[Tony]

Hi, Folks.
Makes you realise what slippery hulls these are.
On Four Sisters (CBL)I have a 4hp Yamaha, which is probably bigger (23kg) than she needs but gives me enough grunt to tow other boats at 5 knots and with its reverse gear,(needed as there is no room to spin the motor around in the well) to back me out of the mud when I am not paying attention....
Range is an issue and the internal tank will keep me going for about an hour and a half at half throttle (c 4.5 knots) I switch over to the external tank for long trips when it makes more sense to motor into the wind than spend hours tacking.
(BTW The engine is quieter than most - no need to raise your voice at cruising revs.)
2/3rds throttle gives me about 6 knots and opening the throttle wide gives me er... 6 knots ! (Hull speed, I think.)
At tick-over I am still doing about 2 knots which means I have to knock it out of gear - or row - if I want to go slower.

Moving off the topic:-
Speaking of rowing, I have 8 foot oars which are an ideal length for storing in the cabin, pinning to the side decks while still in the oar crutches for instant use, manouvering in tight spots and using as punt poles in water too shallow to use the engine. Ideal, that is, for everything EXCEPT serious rowing. I can manage 3 knots in spurts but only about half that for any length of time.
The question is, Would 10 foot oars be any better for rowing at a reasonable speed or just no better - and too long for all the other jobs?
Opinions anyone?

[Michael Rogers]

Re Oar length etc - ask Jeremy, he'll give you an answer which is both erudite and comprehensible (no mean feat when he is dealing with nautical bears of extremely little brain like yours truly). Er - are you there Jeremy? - Tony needs your help.

[Craic]

Tony,
10 foot oars are geared higher, which is good if you have the strength, and they have a flatter angle at which they submerge. With short oars it is disadvantageous that you have to pull with your hands up too high in order to keep the blades under water. We had 8ft. oars on the Drascombes to start with, and changed to 10 ft. oars after the first raid, and stayed with 10ft. ever since. I think the standard oars for BayRaiders are 10 ft. long.

[Julian Swindell]

Claus
You can't do Morbihan tricks in the entrance to Poole harbour. The shore is lined with millionaires' mansions which all have solid steel jetties for their megayachts sticking right out into the main channel. You are stuck in the full current with hundreds of other boats and inevitably (in my experience) the Cross Channel High speed ferry looms into view as soon as I am around. If you don't get out of the way, a harbour master boat will literally lasso you and drag you out of the way, not in a friendly manner. The proper Poole technique is to anchor outside the harbour and wait for the current to change, which it does fairly quickly because of the strange double high tide we have, but often I simply don't have the time to wait. Have to get back for work etc. Once I am retired I will spend much of my life floating at anchor, waiting for the tide. Sadly I haven't got the time at present. Hence the big engine.

[David]

The two things I really didn't like on the Honda is that it is very noisy and doesn't have reverse. I work in and out of pontoons and marinas quite often, and lack of reverse can make that a bit of a challenge.

Hi Julian

Its interesting you mentioned those 2 items about the Honda as I found it quite loud and don't bother speaking to passengers with it running. I haven't mastered the spinning the motor around for reverse yet. I am fortunate in that I don't have to go into any marinas or along side jetties as nearly all my launching and landing is done from a shore. The one time I tried to the spin the motor around my brain and hand become disconnected and I accelerated instead for slowing down. I haven't tried again since though feel I should practice it more. I have enclosed a picture of my BR at my wife's and I's favourite picnic spot.

On the subject of oars Denman Marine supplied me with 2  9ft 6" ones with a turks knot on a foot of leather for the rollick support. I initially thought they were 2 short but Andrew pointed out he had set them up for 2 rowers and once I adjusted them they work fine and I quite enjoy rowing the boat. I am also fortunate in I have no tides or large amounts of other craft to deal with for although I live on a salt water lake the sea entrance is very small and a long way from me(33deg 07S, 151deg 32 43 E).

I retired a month ago and thought I would now get lots of sailing in but I still seem to be very busy though I have great control on choosing my sailing day dependant on the weather

Regards
David
Little Ripple
Lake Macquarie

[Julian Swindell]

David
What a glorious spot. I would just retire there if I had the option.

The Honda is noisy because it is air cooled, so no deadening water layer around it. I went completely schizoid trying to spin it round and use it in reverse. As you say, a go slower twist goes the wrong way round. I once managed to just spin it half way round, jamb it and then accelerated full throttle. Spun me round on the spot and banged me into half a dozen boats. I could see everyone looking at me and wondering "Why did he DO that?"

[Tony]

Hi, David.

You have my deepest sympathy! Fancy having no option but to picnic at a spot like that! Does not bear thinking about.
Just to make you jealous, here is a picture, taken a month or so ago, of the sort of idyllic spot us Brits favour. Yes! That is real ice with real fog over it. Beautiful!
(Sorry its a bit blurred. I g-get  C-c-camera  sh-sh-shake at minus 14 !)
Oh! That isnt an ice breaker, by the way.  Its just the sailing clubs committee boat which they didnt get out of the water fast enough.

[Jeremy]

Speaking of rowing, I have 8 foot oars which are an ideal length for storing in the cabin, pinning to the side decks while still in the oar crutches for instant use, manouvering in tight spots and using as punt poles in water too shallow to use the engine. Ideal, that is, for everything EXCEPT serious rowing. I can manage 3 knots in spurts but only about half that for any length of time.
The question is, Would 10 foot oars be any better for rowing at a reasonable speed or just no better - and too long for all the other jobs?
Opinions anyone?

There are several formulae for estimating oar length, but generally you want oars that have a ratio of inboard length to outboard length of around 2.5 to 2.6 (I think the traditional formula is 7 parts inboard to 18 parts outboard).  It depends a little on the height of the rowlocks and their relative height to the thwart you're rowing from, but generally this sort of ratio is about right.  Inboard length should be about 2 inches longer than half the distance between the rowlocks.

If the distance between the rowlocks is 6ft, then the inboard length needs to be around 3ft 2ins and the total oar length around 11ft 4ins - surprisingly long and probably a bit impractical to stow.  I'd suggest trying some 10ft oars, set with the buttons in the right place to give a 2" overlap at the inboard ends with the oars horizontal.

Jeremy

PS:  Thanks for the kind words, Michael!

[Tony]

Hi, Folks
Thanks for all the input about oars. I still have a lot of questions/ignorance on this so will start a new thread on the subject shortly. Thanks again.

Back to Outboards:

I would dearly love to use a lighter/cheaper/more economical motor – as staunchly advocated by Claus, among others – but remain unconvinced enough to hang on to my 4hp Yam, at least for the time being.

  I have a sneaking idea that "off the peg" motors have props selected to be average performers over a wide range of roles and none of them are really matched for the optimum performance with our type of boats.  I believe that prop pitch roughly equates to gearing on a bicycle and so we are all, in effect, riding "fixed gears". I did this a lot in my cycling youth and know the effect of choosing too high or too low. (knackered knees!)

Is the problem with 2.3hp models that too fine a pitch has the thing noisily revving its head off to give 4 knots? Is my "2 knots and no slower" at tick over because of too coarse a pitch? (I think I would rather have the latter than the former.)
Anyone used "Sail drive" props out there, or knows any way of assessing this problem?

[Jeremy]

Depending on the prop fitted to your motor, the chances are that you might gain an efficiency improvement of up to 50% by changing it for one better matched to your boat.  Prop matching is critical to efficiency, but to do the job properly you need to know the resistance curve for your hull.  I suspect that Nick/Matt may have already modelled this, so if you ask them (or if they are reading this!) maybe they could publish it.

With that curve, plus the prop rpm range and peak torque point for your outboard I could pretty quickly give you the optimum diameter and pitch needed to match the boats thrust/speed requirement.

When I was working through prop designs for my electric Winsome I found that quite a lot of off-the-shelf props struggled to get better than around 40% efficiency.  A well-matched and designed prop can give around 80 to 85% efficiency, so there is a lot to be gained by selecting the right prop for the job.

I suspect that small outboard manufacturers err on the side of fitting props that are too small in diameter with too fine a pitch for best efficiency.  This would make them well-suited to pushing a fat, heavy dinghy, but much less well suited to propelling low resistance sailing boat hull.

Jeremy

[Craic]

... I suspect that small outboard manufacturers err on the side of fitting props that are too small in diameter with too fine a pitch for best efficiency.  This would make them well-suited to pushing a fat, heavy dinghy, but much less well suited to propelling low resistance sailing boat hull.
Jeremy

Jeremy,
I think you err in that you suspect the small outboard manufacturers err. Both the Honda 2.3 and the Suzuki 2.5 have excellent efficiency when pushing the BayRaider, for which their low fuel consumption which started this thread is proof.

Also, these small engines do not have small propellers with very fine pitch. They (I have both) have suprisingly large propellers. The Suzuki has so much pitch it does not reach the max revs when pushing the boat to near hull speed, 5.5 knots.
Reason is they are not as you suggest optimised for pushing fat heavy dinghies, instead they are adapted for pushing lightweight tenders and small inflatables, which is practically their only market.
It so happens that they work so well for the low resistance Raiders too.

Tony,
I see no real point in your pondering changing your existing 4hp against an even smaller engine. You are not racing, and the fuel cost savings won't likely ever compensate your loss from having to buy a new engine and selling your old. Also you'll miss the reverse. In an open Raider you can always jump quickly forward to fender off an unduly fast approaching pontoon, in the cabin boats you are limited there. And then your boat has a high mass due to its cabin and the fixed ballast you carry. Better stay with your old engine.
That the small engines are working perfect for the Raiders does not automatically mean the are also ideal for very different boats like your CBL or Julians BayCruiser.

BTW, the Honda 2.3 is indeed noisy. That is why I recommend the Suzi 2.5. Watercooled, so quieter, and with a good bit more oomph from the same weight, 12kgs.