Centaur - outboard motor

[tarik]

Evening all,


I have bitten the bullet and taken the internal Petter engine out as I want to use the space, I want to fit an outboard motor, I don't intend to do much motoring but will use it mostly for going in and out of the harbour.

What does the team think would be the most suitable outboard to get, I wasn't planning to get a new one but a good reliable 2nd hand engine.

As always many thanks for any advice given.


David

 

[seumask]

Watch out this subject has been aired on here extensivly in the last few years so do a search on the forum for more information.
That said Yamaha 9.9 high thrust is in my opinion the best option. There is/was a forumite who was thinking of selling one, so again do a search if you have not done so already.

 

[VicS]

Evening all,


I have bitten the bullet and taken the internal Petter engine out as I want to use the space, I want to fit an outboard motor, I don't intend to do much motoring but will use it mostly for going in and out of the harbour.

What does the team think would be the most suitable outboard to get, I wasn't planning to get a new one but a good reliable 2nd hand engine.

As always many thanks for any advice given.


David

Quite a high transom on a Centaur therefore I'd suggest an extra long shaft (25") and minimum 8hp with high thrust prop

Might even look at the possibility of an ultra long shaft ( 30") like the yanks use on their curious pontoon boats but I think these may only be available in higher power ratings.

Id suggest remote controls might make an ordinary longshaft ( 20") a practical proposition.


Mentally crazy idea but you could look at the feasibility of constructing a well

 

[Tranona]

As suggested you will need 10 HP. Minimum long shaft. You will find it difficult to operate because when mounted on a bracket at the correct height you will need to hang over the back to reach the controls. So remote controls and electric start will be desirable. Do not expect much performance in anything other than light weather.

 

[Hadenough]

Apart from the fact that I think that it is crazy idea. What exactly do you "want to use the space" for?

 

[dylanwinter]

https://www.youtube.com/watch?v=AQRF2cLPwUk

 

[paul-essex]

I would like 10hp as on my Westerly 25 which is a lot smaller and slimmer I have had a 8 hp (was ok) and have now got a 25hp

 

[William_H]

I think you need to consider a whole lot of compromises in choosing your motor. Firstly are you willing to leave it attached to a transom bracket or do you wish to remove to it inside when leaving the boat or even when sailing.
This question will dictate max weight of the motor.
A small power motor will work quite well when you have no wind. (even 3Hp) Very limited when you want to power into the wind.
Perhaps you are willing to sail into the wind if necessary. So much will depend on the nature of you harbour entrance is there a tide flow of significance?
If you go for a transom bracket then get or make one that is adjustable in height. This will enable it to be pushed as low as possible to minimise prop cavitation when the boat pitches in a sea way.
If you think of putting it in a well I would look at a well open at the transom so motor can be tilted up for sailing.
The board for mounting the motor might be about 40 cms ahead of the original transom. A vast improvement over the typical 40cms aft of the transom of a bracket.
Yes do get a long shaft motor. good luck olewill

 

[Keith 66]

Some years ago when we bought our Sabre 27 her inboard engine was dead. So to get her home i borrowed a lifting outboard bracket & bolted it to the tramsom. The outboard i happened to have was a 5hp Johnson standard shaft. It was workable & with the bracket in the down position worked fine. It had more than enough power to manouevre in the marina & got her up to 4.5 knots in a calm. Ran out of puff going into a head sea but once the sails were up it didnt matter!

 

[prv]

Apart from the fact that I think that it is crazy idea. What exactly do you "want to use the space" for?

On their second boat, the notoriously engineless Pardeys used that space for a kind of bathtub

Pete

 

[Seajet]

Apart from the fact that I think that it is crazy idea. What exactly do you "want to use the space" for?

Primarily, a decent inflatable dinghy.

As well as a foot pump backup, Plan A for inflating it - and deflating it at the last stages for easier stowage - would be a ' 12v hi speed inflator ' - do beware these things MUST be clipped diectly to the battey with the croc clips provided, I knew a ' professional electrician ' who melted the wiring and nearly set his boat on fire using one of these high-amp draw inflators via a switch panel - a definite no-no, go straight to the service / domestic battery.

http://www.force4.co.uk/department/...-high-speed-dinghy-inflator.html#.VwCtejEoGSo

However I have sailed Centaurs a lot over 30 years and I am very much against outboards on the stern - let alone cutting a well.

The well would not work in my opinion as the mount is too high and the leg would be too shallow, + the well would cause tremendous drag, noise and turbulence.

Please note I have had a 22' boat with an outboard well for 38 years.

The idea with my boat is, as soon as in clear water to lift and stow the engine ( a 5hp Mariner 2-stroke is ideal, 4-strokes are very heavy ) then fit a fairing / draining plug - not only does everything suddenly become much quieter, one gains a huge speed boost under sail - I'm talking of passage making speeds, not just a racing nut.

With just the engine in, turned off, sailing with it left in the well is very surprisingly noisy, lets water slosh in the cockpit and knocks 1.5 knots off passage making speed which is extremely significant to

A, enjoyment,

B, progress

I think this is a forum-spinning idea of Dylan's, best to do it properly as Dylan himself has shown using 2 Centaurs to date keeping the inboard engines.

The idea was no doubt to recreate a ' poor man's saildrive ' but that shows little experience with engine wells.

I'd rather sail a Centaur completely engineless and save weight rather than butcher a well into one which is a horrible idea given a hint of design knowledge, I think only ever a conversational proposal.

 

[dylanwinter]

On their second boat, the notoriously engineless Pardeys used that space for a kind of bathtub

Pete

notoriously engineless yet always had a rib with a powerful outboard which could be breasted up to the engineless big boat for moving around harbours.

Incidentally, back to the subject

did a fair amount of work on this

6hp is enough

10hp is better

outbard bracket is fine - no problems

a well would be even better

I made some fairly detailed drawings

but was then loaned a centaur with a good inboard for £1

I had worked out that three good blokes could convert a centaur from an inboard to a well in three days

http://www.keepturningleft.co.uk/blogs/centaur-well-three-blokes-three-days-300/


you will find that people will get a bit hot under the collar at the idea of such a thing

 

[Iliade]

The transom on Centaurs is only just thick enough to bear a four stroke ~10 hp outboard. You will want to use a large backing pad inside and out to spread the load.

It was not on the Centaur that my motor punched through the transom, but the Centaur transom flexed alarmingly at times - Much happier with a new inboard in the Centaur.

 

[dylanwinter]

The transom on Centaurs is only just thick enough to bear a four stroke ~10 hp outboard. You will want to use a large backing pad inside and out to spread the load.

It was not on the Centaur that my motor punched through the transom, but the Centaur transom flexed alarmingly at times - Much happier with a new inboard in the Centaur.

Harmony had some extra timbers glassed into the inside of the transome

no flexing of transome

I agree an inboard is better

but as replacing the lump by a pro will cost you over 6K then better to be sailing a Centaur with an outboard on the back rather than not saili ng one that is sat in a yard while you are saving up.

Did you ever get cavitaion?

It is part of the game with an outboard on the back

had a eboat and a sonata - both cavitated

having spwnt a hear sailing around with an outboard on a bracket on the back of harmony I don't think that cavitation woud be much of a problem.

Incidentally,

2.3 hp

centaur

3 knots

 

[Seajet]

Dylan,

Your Sonata and E-Boats both had transom hung engines not wells, so as on the end with pitching effect, not difficult to imagine ' cavitation ' .

BTW was that true cavitation or ' engine right at the surface working in froth ' ?

On the A22 I can get true cavitation in reverse due to the through-hub engine exhaust blowing bubbles over the prop', the answer sems to be to use it in short bursts to get things going then throttle back when she'll quite happily reverse as long as one doesn't go too fast to cause the tiller to slam over.

This seems an under-used technique, what with the bows blowing away downwind as on most boats it can make life a lot easier reversing up to moorings or into marina berths in some stiff / cross wind conditions and one can see what one's doing close up !

 

[rob2]

I suppose my opinions reflect my age... I can't understanbd why certain people think outboards are reliable - they never have been for me, yet I can get an inboard diesel running unless something is actually broken on it. Dylan keeps referring to the price of new inboards and I agree that it is difficult to accept that a SMALL engine sells for the on-the-road price of a new car. But then again, I can buy a lawnmower for £100, but the smallest of outboards start at six times the price. Incidentally, my lawnmower won't start...

Rob.

 

[VicS]

Thats not true cavitation, that's ventilation with exhaust gas. Cavitation is caused by bubbles, or voids, containing just water vapour forming on the low pressure side of a propeller blade. In effect low temperature boiling due to the low pressure. My Yachtwin engine is designed so that ventilation by exhaust gas does not happen

 

[CAPTAIN FANTASTIC]

New generation outboards perform much better than the old two stroke, high rev, low torque, outdated outboards.

 

[jwilson]

When Centaurs were first sold a 9.5 hp outboard was on the options list instead of an inboard as a cheaper option. I doubt many were sold with this though as you have to remember that at the end of the 1960s, for the average cruising sailor a Centaur was quite a "big boat" and only quite rich people could afford one new, and they mostly coughed up the extra for an inboard.

It was the age of 16-22 ft plywood cruisers, with 24 ft Eventides (also plywood) another bigger boat. A Nicholson 32 was a seriously big boat for most sailing clubs then.

I have never actually seen a Centaur with what looked like a suitable outboard bracket for a 9-10 hp outboard: but probably it would have been quite a substantial one, possibly one that slid up the transom on rails like some on several 1960s plywood boats.

 

[doug748]

My tuppence is:

The outboard will be fine and you will sail more and end up a better sailor.

I would go for 8hp and up to 10 but no more (think of your back), above that the law of diminishing returns tends to set in. A two stroke certainly, something like a Tohatsu 9.9 long shaft or an old Mercury. If all I could get, quickly and cheaply, was 5hp I would launch with that rather than miss the season.

The well is a grand idea for someone with the time and will, I am sure it would work fine. We all look forward to seeing it done but your plan is good.
The only glitch is that asking prices for 2 strokes are sometimes a bit potty.
As always, do tell us how you got on with it.