Outboard to inboard conversion ?

[Madhatter]

I am considering putting the outboard - inboard on my new boat (new old boat ) and now would be a good time to do it as it will be going through a full refurbishment over the winter.The boat is a Tucker Debutante 21.
Do the panel have any advice/comments on this ?
Derrick

 

[Egbod]

Inboard Outboard

I like your idea.
My previous boat had a transom hung outboard which worked better on one tack when motorsailing.
Friends have boats with as outboard well with the outboard permanently down which is convenient but slows them by about 1 knot of speed when sailing. Or you remove it and store it somewhere- not easy.
My current boat has the best of both worlds. The outboard is in a well at the back of the cockpit yet can be tipped up with the outboard clear of the water with the leg locating in a slot in the transom. The rudder has been changed to a two rudder system to allow for this. The system is well thought out and works very well. The only downsides seems to be the engine noise of the outboard is louder (I try to sail as much as possible anyway) and there is noise from water turbulance which I think is mainly that you can hear it because it is not outside the transom. Curiously the noise is loudest at about 3 knots and is not noticable at high or slow speed. The water noise is just different and not too much of a problem. I might look at some sort of baffle I can slip in to smooth the water flow It means engine checks are easier and the weight is nearer the middle of the boat.
If you would like more information I can sort out some photos to PM you.

 

[DaveS]

Do I understand correctly that you want to use your existing outboard motor but mounted in an inboard well? If not, ignore the rest of this.

My previous boat, an Etap 22, had this arrangement. It had definite advantages over an outboard over the stern, particularly if the boat was pitching, avoiding discomfort while operating it and also the prop leaving the water. Maintenance was more convenient too, with less chance of losing bits.

Building a well has I am sure been the subject of articles, but I can't recall seeing one for some time. Obviously any construction that involves cutting a hole in a perfectly sound hull is a bit daunting, and it goes without saying that the construction has to be perfectly sound and strong enough to take the loads. If you are thinking of removing the motor while sailing (probably more relevant to racers and ocean crossers than coastal potterers) then a plug to fit the hole and make the hull flush is a good thing.

One tip I would offer if building a well is to size it generously. Outboards tend not to have a long life and your choice of replacement will be governed by what will fit.

A critical point is exhaust. If the outboard exhausts through the propeller hub then you might just get away with it, but see below. If it does not, you definitely need to think about venting arrangements since, apart from the stink and possible health issues, the exhaust gasses will accumulate in the well and be breathed in by the engine which after a few minutes will start to choke. This issue is worst at idle - and while idling a hub vent is no better than any other - and while manoeuvring slowly. It took me quite a while to realise what was going on, and fitting a suitable fan and duct was very high on my "to do" list when instead I sold the boat.

 

[Madhatter]

Thank you both for your replies .

DaveS,
exactly what I want to do ,and you have given me food for thought.

Egbod, PM sent

 

[William_H]

Outboard mounting

I prefer my o/b on the transom bracket with adjustable height so that o/b can be lower if pitching or someone is on the foredeck or in smooth water with heavy cockpit load raise the o/b so it is not too deep.
However I use the o/b very little so my ideas might not align with your needs.
Presumably you have the o/b on an extended bracket and don't like the problems of stern rising causing cavitation when pitching.

One boat around here has the o/b right on the transom which brings it further forward but is thn not easily adjustable for height. You need the o/b in the middle so must have twin rudders or a rudder forward of transom. A variation is a big slot cut in the transom with the o/b about 40cms forward of the transom and a false transom to mount the engine on. Both these ideas allow for the o/b to be tilted for sailing and ease of operation and maintenance. However in both cases the o/b is not easily adjusted for height and will still rise and fall with pitching though to a lesser degree than being mounted aft of transom as mine is.
One friend has a hole cut in the bottom of the port locker. This means you don't lose space in the floor of the cockpit but does mean you can't tilt the motor and you get deeper thrust on starboard tack.

So it is up to you as to how much you want to get good thrust in pitching conditions versus the huge project of cutting and building motor mounts in the hull. Not for me though. olewill

 

[DownWest]

MH, a few thoughts. Both I and a friend have outboards in wells. Neither have through hub exausts and mine has the smallest cut out that the prop will pass through, while the other has a rubber flap that closes round the leg above the cavitation plate. No fume problems worth talking about.
In your ply boat, an offset well might be advisable, due to the hog in the centre. Cutting through the keel/hog might not be a good idea, but easy off to one side of it. The idea of twin rudders sounds good, look at some of the smaller French boats for ideas, or the Red Fox. The threads here about shape and ballance (LakeSailer) wll help and you don't need hinged blades.

 

[Zagato]

I had a 6HP Honda in a ready made well in a Drascombe Longboat, I was never quite happy with it because depending on the speed you where doing the water would lower to the horizontal plates above the propeller. The engine was correct and I would not go to fast, it was just the way the water travelled under the boat at a certain speed. The water would lower probably about 12" I was always worried it was to low for the cooling water intake. Another issue can be flooding of the well when moored, I know this was an issue on Marieholm IF boats.

An outboard has got to be so much easier to maintain etc so I think it is a good idea - good luck.

 

[Seajet]

Outboard well

I’d think an offset well with your original rudder ( unless it fouls the prop’ ) would be ideal, less hassle and stronger than twin rudders, which would look pretty odd on a Deb’, + the problems of a linkage without slack, and wear, vulnerable when drying especially if splayed, etc.

I’m pretty sure the similar Mystic had a well ? I can’t remember details or if it was a good arrangement though, it was the first boat I'd ever sailed on and I was 7-8 yrs old the first trip.

I have a well on my Anderson 22, it’s slightly offset to port; I don’t get any asymmetric handling problems.

If sailing for more than a few minutes, the engine comes out and is stowed in a cockpit locker, in this case to port, as it’s the same side of the pivoted lifting tiller, and away from the autopilot which is usually to starboard – though of course they can usually be switched to work on the port side if necessary.

Then the standard fairing plug is fitted, giving a smooth hull; very handy not just for performance, but avoids collecting lobster pots, weed etc around the prop’.

If one collects anything nasty around the prop’ when motoring, the engine can easily be raised and an old breadknife used to clear it.

With the engine in there’s only slight turbulence, but with no engine or plug there’s a lot of turbulence and noise.

A chum with an Anderson tried a plug with a cut-out fitted with a rubber gaiter to take the outboard leg, to see if a non-turbulent low drag ‘engine in mode’ rather like a saildrive could be achieved, but the engine started to overheat, we’re not sure if it was related or not but as it was too fiddly and the normal set-up works fine we abandoned the experiment.

Incidentally, I run the Anderson Owners Association, www.anderson22class.co.uk

We have spare well plugs, they come out at £196.00 with a stainless Elvstrom bailer & wooden handle – that’s cost price, no profit - , or a lot less just for the moulding; if any use you’d be welcome to try one.

If it looked like a go-er re. Hull shape, it would of course be best if the well was made to suit !

My engine is a 5hp Mariner 2 stroke, great engine with plenty of power, but light enough to lift easily. This is short shaft which is fine on the Anderson; you may need a long shaft, but try to avoid it as it’s a lot more difficult to stow.

When I bought my Mariner new it had both internal and external tanks. I removed the internal one, partly to reduce weight a fraction but mainly so that there’s no fuel to spill in the locker.

Interestingly, this winter lay up I helped another A22 with the same engine but internal tank ( nearly full ) only; it was noticeably heavier, I could feel t straight away.

When stopping the engine I usually take off the fuel line and let it run dry, so there’s no fuel in the carb’ to leak.

This doesn’t affect starting next time in the slightest.

Beware if using a 4-stroke engine, a lot don’t like being stowed flat, as lube’ oil can flow into the combustion chamber causing an inconvenient and expensive hydraulic lock; they’re heavy too !

Usually when taking the engine out I stand it for about 20 seconds on the cockpit sole to drain water.

All the engine & plug in-out operations – which are very quick and easy once one develops a method – are done with the pivoting tiller slightly raised with either crew or autopilot steering.

My Mariner 5 gives a top speed around 5.5knots, I have happily motored across the Channel in calms several times, I get a pretty consistent 2.5 hours per gallon at 5 knots, a lot more efficient if motor sailing in very light winds.

With a through hub exhaust I get very little in the way of fumes, certainly nothing like choking the engine. I think the lean mixture ( book says 100:1, I use 75:1 ) helps, compared to a smoky 25:1 Seagull etc !

The comment about making the well strong is quite right of course, there’s a lot of load especially fore & aft at the engine clamps.

I’d never consider a boat with an engine on the transom now, I can get at the controls easily, work on it without riskng self or tools over the end, and the prop’ has only left the water once I can remember, that was when hitting a line of white water at the N end of the Little Russell…

As my cockpit drains into the well, I have a dinghy style self bailer in the plug, which has never been overwhelmed yet, and has the advantage of being closeable, in the event of a lot of people in the cockpit when the boat is stationary or moving slowly, when a small amount of water can splash in through the drains.

In heavy weather and at the mooring ( not a go at your recent sad experience, hope it is working out OK ) I leave the plug out, giving a massive cockpit drain.

The fuel tank lives in a locker next to the well, I use an anti-splash funnel and stop the engine when topping up; also I fitted an auto extinguisher in the transom coaming above the fuel, I doubt it would stop a real fire but I’d rather have it than not ! I have a 'Tannoy' vent on the lid of the fuel locker for obvious reasons, with the transparent cetre painted over to avoid beaming sunlight directly onto the tank - it's also a good use of an old old Tannoy vent, ( there's one above the chart table / cooker ) - U/V always discolours the transparent bit anyway ! Both vents, over the charts and over the fuel, are the closeable type which I think is important.

Hope that’s some use, an interesting & worthwhile project for you, don’t forget to take lots of photo’s !

Cockpit with well to port, ventilated fuel to stbd - the ventilator is closeable for heavy weather; NB cockpit drains into well, with 'hit & miss' shutter.

Non-standard hinged stainless lids, the advantage is I don't need to take lids on & off and find space to put them.

Well plug with self bailer in open position, in this shot the forward end is to the right.

Well plug showing Elvstrom Super-Max bailer ( at deepest point) and handle, which must be strong. Forward end to left.

The plug is held down ( it and the well are tapered, so the plug won't drop straight through ! ) by a simple pivotting wooden strut bolted through the well side, with a bolt & rubber seals each side, safely above water level.

 

[Madhatter]

Thank you all for your replies.
I see that Tristan Jones had a well mounted one on his Debutante :

[/IMG]

Because this is from scratch the design would be to suit and I do understand the structural problems ,I am considering a sliding mount that could be adjusted according to needs.

Seajet ,your contribution is once again food for thought ,thanks.

 

[Madhatter]

As you can see the cockpit is a long way from the stern and plenty of room in the rear lockers

[/IMG]

 

[Seajet]

Hi MadHatter,

A sliding track may well be worth a try; might have problems with fouling the tiller ?

The Hunter Impala had some system of swinging the o/b in its' well up sideways, but I haven't got a good look around one - may well be worth you doing so if there should happen to be one handy.

When we were going to put the Anderson back into production ( do you know anyone who'd be interested in the production moulds ? We have a part complete boat with them too, but she may have a buyer this afternoon unless we can get interest in the moulds which she's be very useful with ) - I investigated all sorts of rails to self stow the engine etc, it's do-able but we decided initially at least to keep it simple with the original set-up.

One option I was very keen on, but doesn't suit an Anderson and would be expensive ( and at current readily available technology limits ) was an electric engine, this would need a battery bank incorporated into part of the ballast configuration...

 

[Seajet]

Madhatter,

I've thought of a detail which might be worth bearing in mind; I have a 'Tannoy' style ventilator in the lid of the fuel locker for obvious reasons.

This position had originally been occupied by an expensive day and night solar powered closeable vent set as an extractor fan ( self contained chargeable battery job ).

The salesman at the Boat Show assured me it was tested 'explosion safe' spark-free, a real term I had learned while photographing inside aircraft full of fuel, with a special safety light.

After a year or two the vent packed up, but naturally the makers packed up first; when I sent the vent to a chum who's an ace aircraft electrician he nearly died on the spot, no way was it spark-safe, so I'm lucky I'm not in orbit right now - as the salesman will be if I ever meet him; I was thick not to get something in writing.

I checked all the suppliers of solar powered vents I could find, and as of a few years ago no manufacturer would guarantee their product for this use.

So I use an ECS Tannoy vent, non solar;I considered a motorboat style bilge blower fan for a few seconds, but it seems overkill and it's still electrics around the fuel.

I never notice any smell of petrol fumes around the fuel locker, and I probably would if they were there, I'm quite alert to this, long story.

The central transparent part of the vent is painted over to avoid sunlight beaming onto the fuel tank - I know there are solid plastic centres available, but as the Anderson has a Tannoy vent above the chart table / cooker and the transparent bits discolour through U / V in time, this is a good use of old ventilators !

Both vents, above chart and fuel tank are bolted on and the closeable type which I feel is important.

Closing these vents, among other things, is on a laminated check-list for heavy weather as an aide memoire for me, or guide for crew if I'm incapacitated etc.

Also the fuel locker lid, being a bit vulnerable anywhere in the cockpit let alone next to the well, clamps down via an over-centre catch onto a rubber strip; the adhesive backed 'Hatchseal' stuff, assisted by Araldite.

The over-centre catch also has the facility of being padlocked, which while I've never used it might be handy if I ever end up in a particularly yobbo - likely place, or if / when I realise an ambition and take the boat through the French Canals I worked on for a while.

This lid and seal fit has survived a couple of cockpit-filling poopings, one a proper heavy weather event I can talk about at the club bar, the other a surprise job in good weather off Anvil Point, Dorset, when I was lulled into a false sense of security and a bit of an overfall slopped into the cockpit, just enough to soak self & girlfriend and b***er the radio...