The Unified Corribee Website

BMW D7

The BMW D7 was the factory fitted inboard for many boats. Everything you ever wanted to know about the BMW D7 can be found here:

http://wavelength30.zxq.net/BMWD7.htm

Volvo Penta MD 2010

A brief description of a Volvo Penta MD 2010 installation can be found here:

http://groups.yahoo.com/group/CorribeeCoromandel/message/54

Yanmar 1GM10

Fitting a Yanmar 1GM10 single-cylinder diesel engine to a late mk2 bilge-keel Corribee – some details including drawings and photos. The installation details include the fitting of the propeller shaft and tube, along with a Halyard Aquadrive flexible drive coupling.

fig 1.1: Schematic view of engine, showing position of engine mounts

When the engine mounts are attached, their underside is on the same level as the centre line of the gearbox output shaft. This means that the height of the engine beds is in the same plane as the drive shaft.

fig 1.2: Schematic view of Halyard Aquadrive model 20 000

The Aquadrive can accommodate an angular change in the drive line. More importantly for a small boat such as the Corribee is that the vibration is not transmitted to the prop shaft and thence to the hull, meaning that the installation is quieter and imposes less stress on the hull moulding.

Drawings:

The following drawings show the engine layout both with and without the Aquadrive fitted. Obviously, with the Aquadrive in place the engine can be positioned on a horizontal plane, making it slightly lower. Please note that the dimensions are approximate – I have found that hull thickness and bulkhead positions vary between boats. On my own Corribee the drawings are accurate to around 30mm, mainly because of the difficulty of measuring the lines accurately and of relating the outside dimensions to the inside dimensions.

However, the drawings show that, with the engine in the position shown, tucked under the bridge deck at the front of the cockpit, there is about 400mm between the gearbox output flange and the point at which the shaft tube enters the hull. This should be enough to install an Aquadrive (if you so wish) along with a stern gland.

A GRP stern tube is recommended (unless you already have an alternative installed) as it is so easy to bond into place.

Fig 2.1(above) Yanmar with conventional prop shaft and rigid coupling.

Fig 2.2 (above) Yanmar 1GM10 with Aquadrive prop shaft coupling.

Installing the stern tube and modifying the skeg :

An extension piece can be moulded from epoxy and glass cloth, formed around a Styrofoam core. Styrofoam is easy to shape with a saw and glass paper. Polyfilla (or similar) can be used for filling and smoothing if you have trouble getting a smooth finish.

This skeg was formed with 2 layers of bi-directional woven glass cloth and SP106 Epoxy Resin. It’s really worth investing in all the protective gear such as rubber gloves and epoxy hand cleaner before you start. A wooden or plastic spatula is a good tool for laying up – it helps in forcing the resin into the cloth and ensuring it is completely saturated.

Fig 3.1 (above): The foam core and glass cloth cut to size, ready to start laying up. I found the paint brush fairly useless for this, as it failed to force the resin into the weave of the cloth, so I used the mixing spatula instead. It’s important to make certain that the cloth is totally saturated with resin.

Fig 3.2 (above): Cling film (or polythene sheet) is useful to protect anything you don’t want to stick epoxy to. SP Systems resin and hardener was used, with bi-axial glass cloth. Ordinary chopped strand mat can’t be used with epoxy as it contains a styrene binder that epoxy can’t dissolve. Methylated spirits is good for cleaning up uncured epoxy.

Fig 3.3 (above): A trial fit of the extension piece. If you make it the correct thickness it should just wedge into place on the leading edge of the existing skeg. An angle grinder with an abrasive disc (40 or 60 grit) has been used to clean up the area which will be bonded – but the final fitting won’t be done until the stern tube is in place. When that time comes the gel coat will be sanded off to give a good bond to the the underlying GRP of the hull and skeg. The red lines are markers in the woven glass cloth which show the direction of weave. For maximum strength the layers of glass need to be laid at different angles.

Fig 3.4 (above): The worst bit – drilling the hole for the stern tube. Measure thrice, check twice and cut once. I cut the hole by chain-drilling with a 5mm drill and cleaning up with a coarse half-round file. The hole has to be elliptical in shape because of the angle of the tube. I used a marker pen to draw the angle of the tube (as seen on the leading edge of the skeg). When I cut into the skeg itself I found it was hollow. Luckily, there was just enough room for me to slide the stern tube through the skeg (I had to smooth a few lumps down with a coarse file to help it fit).

Stern tube details :

A GRP or similar composite stern tube is recommended (unless an alternative is already installed) as it is so easy to bond into place. I used a carbon-fibre/epoxy composite, which sounds very technical, but is in fact part of the mast of a windsurfer. Testing an offcut it seems to be incredibly strong. My tube (shown below) is 640 mm long, 38mm dia at the left hand end (inboard) and 44mm dia at the outboard end. The red tape marks the position where it enters the hull and the forward end of the skeg. Ready-made GRP stern tubes can be bought from suppliers such as Lancing Marine or ASAP Supplies.

The tube needs a cutlass bearing at the outboard end – either a standard bought component or one can be turned up from a suitable material such as Vesconite – a material which doesn’t swell in water like most plastics do, and which happily copes with aggressive environments. My last boat had a Vesconite cutlass bearing, which showed no measurable wear after 6 years of use. The bearing can be an interference fit in the tube, and you might want to fit a stainless grub screw just in case.

At the inboard end a stern gland has to be fitted to keep the water out. There are several different types.I initially planned to use the traditional type which is bonded to the stern tube. Epoxy resin is excellent at bonding the metal stern gland housing to the composite tube, provided it is thoroughly degreased with acetone or SP Systems solvent. It helps to apply a coat of epoxy resin to the mating surface and abrade it with coarse glasspaper while the resin is wet – this ensures the epoxy has absolutely clean, unoxidised metal to adhere to. After discussing with a number of people I decided to use a stern gland with a rubber hose connector – the short length of tough reinforced hose allows the gland to float around the end of the stern tube. This would be the best solution for engine installations that don’t use an Aquadrive, as the greater freedom of movement of the prop shaft will result in less stress on the whole drive train. This is the type shown here (though in reality it would be fitted with a screw-cup greaser – see the photos of the real thing on the following pages):

Cutlass Bearing:

Trial fitting of the prop shaft (3/4″ 316 stainless steel, from Lancing Marine, supplied with a 1:10 taper and machined with a keyway). My drawings indicated that I needed an overall length of 845 mm, but as the shaft was priced in multiples of 300mm I asked Lancing Marine to supply a 900mm and not to cut it, in case my measurements were wrong. The trial fitting showed that it needs 55mm cutting off at the gearbox end – oh well.

The photo above also shows the Vesconite bearing in the end of the tube, held in place by an M5 pan-head machine screw.

Fitting the Aquadrive:

Halyard supply a drawing giving the dimensions of the thrust bulkhead needed. They recommend galvanised steel plate or grp for this, but 1″ marine ply should easily be strong enough, and is much easier to cut to the correct shape. I sealed it with a coating of epoxy resin, and positioned it using a bed of Isopon P38 filler. It will be bonded to the hull with epoxy and glass cloth. Not shown here is a short length of hose which is placed underneath the ply to act as a limber hole, to allow water to drain through to the bilge, rather than lodging behind the ply.

The cockpit drains have been reconnected temporarily without the seacocks – I had to remove them for access but at this stage the boat wasn’t covered.

The vertical plywood panels left and right are the sides of the quarter berths – you can just see where the original 6mm ply bulkhead was glassed to these at each side.

Aquadrive and stern gear access :

Access to the Aquadrive and stern gland will be almost impossible from inside the cabin, and totally impossible once the engine is installed. I looked at a number of off-the-shelf hatches but they were either too expensive or not designed to be stood on. The cockpit sole also has a slight camber which would make it difficult to fit. The alternative is to make one – cut the shape out with a jigsaw fitted with a metal cutting blade. The flange can then be marked out on 12mm ply.

Making the hatch:

The hatch itself is obviously make from the cut out section of cockpit floor. Because I partially cut through the strengthening stringers I had to do a bit of grinding and grp work to tidy things up. The flange is fitted to the floor with 6mm stainless csk machine screws and a good fillet of thickened epoxy resin to bond it in permanently. The hatch is secured with 8mm csk machine screws, with ‘Bighead’ captive nuts bonded to the underside of the flange. A rubber seal will be bonded to the lip of the flange to make it watertight.

Engine beds :

I was originally going to make the engine beds by laminating solid pieces of timber to get the required depth, using coach screws to fix the mountings down. I decided against this, instead making each bed with two pieces of 12mm marine ply and a rebated hardwood top, glued together with epoxy resin. At this stage I have only glued one of the two ply sides on – the other piece is just screwed in position. They have yet to be fitted and have been cut oversize. They should be easy to cut when fitting as I’ll be able to use a jigsaw. Solid engine beds of this thickness would be more difficult to cut on site.

A4 stainless bolts hold the engine mounts in place, and these locate into a 6mm thick stainless strip drilled and tapped at the correct positions. The dimensions were taken from the Yanmar leaflet, which has a very small dimensioned sketch of the 1GM10 on the back. To stop the strip dropping down when the bolts are removed I glued a couple of strips on the inside faces of the ply – the photo below shows it being slid into position, resting on these strips:

Preparing to install the engine beds :

To make sure the beds are installed in the right place I made up a former, again using the dimensions from the Yanmar 1GM10 leaflet. The top surface of the beds should be about 10mm below the drive coupling centre-line (it can be altered by raising or lowering the nuts on the engine mounting studs). I used a sheet of scrap 6mm ply to make the former – this should allow a little adjustment for the final installation.

Engine beds continued:

The first step was to remove the sides of the conpanionway structure – I marked out as carefully as I could and cut with a jigsaw. I am keeping these bits to make the engine box later. I also cut out the aft section of grp cockpit sole, using a Dremel fitted with a thin cutting wheel. Compared with an angle grinder it is slower and I used about 10 of these little discs, but it gives a very fine cut and much less dust. I had a vacuum cleaner nozzle positioned very close to the cut, as well as goggles and those thin surgical rubber gloves.

I made the engine beds deliberately deeper than necessary so I could trim them to the correct profile and height. I was far too cautious – made them far too deep and wasted some ply, but that’s better than making them too small. I bedded them down onto a very generous thickness of epoxy (SP Systems 106 and microfibres), using the excess to form a fillet on each face. I used a very thin shaped batten to reach inside each of the ‘box’ structures and smooth the epoxy into a radius.

Three layers of 600 gsm biaxial cloth layed up with epoxy resin was used to glass the beds in – the original grp was cleaned with an abrasive disc on the Dremel followed by a good swab down with acetone. The Aquadrive thrust mount was given four layers both sides.

This bit of the hull will be difficult to reach when the engine is in place, so after a thorough clean with white spirit and acetone I gave it a couple of coats of Blakes bilge and locker paint.

Engine installation:

The engine arrived in a packing crate – I took the top off it and slid it up a scaffold plank onto the edge of the cockpit. With some support under the boom and a small ratchet pulley we swung it over the companionway and lowered it down. The quoted dry weight is 71 kg (156 lbs) – a bit too much for one person to manage, but ok with two of us and the ratchet winch.

Mildly annoying was the discrepancy in the dimensions internally – the engine sits on the centre line of the hull to within a millimetre or two (as far as I can tell). However, the internal mouldings for the berths are different, with the edge of the port berth being closer to the centre than the starboard berth. This is why the gap each side of the engine beds looks a bit off. On the plus side, there is a lot more room around the engine than I originally imagined – it should be easy to service with a lift-off engine box. It extends forward about 90mm further than the original companionway steps

Engine installation, continued:

The work shown here took a long time – it was difficult to plan it all out in advance and I spent a long time deciding where things should go in an attempt to make maintenance as easy as possible, given the confined space in which everything had to fit.

With the engine in place I was able to couple up the Aquadrive and shaft to make a final check on alignment, complete the cutting out of the propellor aperture and fix on the skeg extension piece. This was a time-consuming job, partly because I was working in fairly primitive conditions and partly because I didn’t apply any epoxy after midday – so it cured before the temperature dropped in the evening. Fortunately the daytime temperatures were high for the time of year, around 17 – 18 oC (epoxy struggles to cure below about 15 oC).

The small space under the cockpit floor made it a bit tricky to squeeze everything in, particularly the Vetus water lock. This is fairly essential as it helps to prevent water flooding back up the exhaust pipe into the engine. It is not as low down as I’d like but this is the only place it will fit. I bonded three eye-bolts inside the hull and used some nylon cord to tie it in place. All the exhaust hose joints are double-clipped as the pipe is fairly stiff and heavy.

Key to these two photos:

1 – Cockpit drains (hoses not yet fitted)

2 – Exhaust hose

3 – Vetus water lock

4 – Halyard Aquadrive

5 – Stern gland stuffing box and cup greaser

6 – Cooling water inlet

All these components are expensive items. Water locks and exhaust hose can often be found at boat jumbles. For peace of mind I bought the seacocks new from ASAP (the only way you can guarantee the material they’re made from).

Not visible in the above photos are the copper fuel feed and return lines, which run under the cockpit floor and are clipped to the plywood sides. The engine cooling water inlet pipe leads to a small remote filter, fixed to the side of the engine box – accessible from just inside the companionway. It has a clear top to make a visual inspection easy.

Engine installation, continued:

After the final fitting of the shaft I was able to prime the new skeg ready for antifouling and fit the propeller.

Finding somewhere to put the panel caused a bit of head scratching – I didn’t want to put it outside. The obvious place was under the bridge deck – I won’t be able to see it of course, but the warning buzzers are loud. The panel can be removed fairly easily for access to the engine. If it proves to be a completely impractical position I’ll have to think again.

I used the original companionway sides to form the engine box by bonding an extra strip on the back edge (where I cut it originally) approx 80mm wide. The front of the box (originally held in place by the lower step) is fixed on to the sides with brass wing nuts, with the top step sitting on short battens and screwed from the sides. There is still some cosmetic work to do to tidy it all up. The whole structure only takes up about 100mm more of the cabin space compared to the original.

Fuel tanks are another potentially expensive item, so I opted for a secondhand outboard tank. The existing fuel feed is a BSP thread so it will accept a conventional hosetail to connect to the copper feed pipe. The fuel return pipe will be fitted next to the feed pipe (getting the backnut on the fitting could be tricky!). The tank is fitted in the stern locker on the port side, sitting on a plywood shelf bonded to the hull and bulkhead. Eye-bolts, a cleat and some 6mm cord hold it in place.

After a little thought, I decided to blank off the existing tank outlet as it is a plastic moulding and might give air leakage problems. Instead I drilled 2 holes and fitted a brass1/4″BSP connector for the fuel return pipe and a 5/16″BSP connector for the feed pipe (which reaches down to within about 25mm of the bottom of the tank). This connects via a ball valve and a length of flexible fuel hose to the primary filter/seperator. The tank is easy to remove for cleaning and the filter is easy to access if I need to drain off any water or change the element. The 1GM10 engine is also fitted with a secondary filter. I still need to fit 2 blanking plugs in the spare filter inlet/outlet holes and a hose clip on the flexible fuel hose. (Note: I have since fitted a purpose made 30l tank to replace the converted outboard one – branded ‘Nuovo Rade’ and available from some of the larger on-line chandleries).

One of the last jobs on the engine was to fit an anti-siphon loop to the cooling system. I made up an unequal tee (13 x 6 x 13 mm) in stainless steel and inserting it in the cooling line just before the exhaust injection point. The small bore of the tee is connected to a thin tube which exits at gunwhale level amidships. As well as making sure that water can’t be siphoned into the engine it acts as a tell-tale, making it easy to check that the cooling water system is working properly. An engine test was carried out while still ashore – a tube from a bucket connected to the water pump provided the cooling water. One bucketful allows the engine to run for about four minutes. In all, I ran the engine for about 15 minutes like this, enabling me to check that the fuel system was properly bled and there were no major leaks in the exhaust system.

Although there are still a few jobs left to do (about 101 I think) I came to the point where I couldn’t delay the launch any more. Clareen was jammed in the furthest corner of the yard and Andy (the yards owner) had to crane her out over the top of a large Westerly. The warning buzzer on the crane (which indicates the safe working load) provided the accompaniment while we scurried round with ropes to stop it swinging about too much.

Safely on the launching trolley, there was enough time left to bend on the main and antifoul the underside of the bilge keels – not a job which gets done very often. It was too windy to put the jib on singlehanded.

Safely tied up on the pontoon, with only a couple of minor problems. The cooling water wasn’t pumping initially because of an airlock, and the strainer needed priming. And, following the on-shore engine test, some idiot had forgotten to tighten a hose clip properly on the water pump. After this was sorted I ran the engine for 45 minutes in gear while tied up to the pontoon without any further problems. Sighs of relief all round.

Cooling water alarm

The engine obviously requires a constant flow of cooling water. This can be interupted by something like a polythene bag blocking the inlet, or a failure of the water pump impeller. The circuit shown will give an immediate warning if the cooling water stops flowing and the engine can be shut down before any damage occurs.

Components needed:

From CPC, http://cpc.farnell.com

SN35600 Liquid flow switch (approx £13.00)

From Rapid Electronics, http://www.rapid.co.uk

10k, 2k2 and 330R resistors

BFY51 transistor

5mm clear red led

12v buzzer

The circuit was made with copper-clad circuit board, machined to the pattern shown above. It could just as easily be laid out on Veroboard or with self adhesive copper tape. Flying leads or plugs and sockets can be used to make the external connections. I had some 2mm plugs and sockets (probably from RS Components) so used these for the connections to the power supply and the flow switch.

The circuit was stuck in a plastic box and fitted onto the control panel. The positive supply was taken from the back of the ignition switch.

The flow switch has to be installed so that the switch unit is uppermost. The inlet hose is 1/2″ inside diameter, approximately the same as the inlet on the water pump. The water inlet strainer, filter and hose I’d already fitted were 3/4″ so I used a reducer on the inlet side of the flow switch.

Source: corribee.org 19/6/2009

Fitting a Yanmar 1GM 10 into a Corribee Mk 2

Yanmar 1GM 10 Data Sheet

We never did like outboard motors, and have always thought that an outboard spoils the lines of a Corribee. Having no engine is unthinkable – we are not good enough sailors and like most people in the modern world have too many time pressures to wait for fair tides. Over the years we have examined all the possible inboards that could fit in to a Corribee, and their price tags, and have been convinced that it would be quite uneconomical to install one. It would in fact make better sense to sell one’s present boat and buy a Corribee with an inboard engine. But we have sold Nyoni once before, and when we bought her back we said we would not do that again.

The BMW D7 is the inboard motor installed into Corribees from new, and the owners we talked to were very satisfied with them. The snag is that, like the Corribee itself, they are no longer made. Nor is the Seagull sail drive, but no one in their right mind would install one of them. The smallest marine engine we could find was the Yanmar 9hp diesel.

Then last year we heard that Andy Rose had installed a Yanmar 9 hp diesel in Nampara, a mark II Corribee with much the same specification as Nyoni. David rang him and there followed several technical discussions on the fitting of such an engine. Andy did most of the work himself but he also consulted Marine Power, Bursledon, on the Hamble, whom he found most helpful when he ran into difficulties. He recommended them very highly.

So one Saturday in the summer we drove down to Bursledon to discuss engine fitting. They had 2 Yanmars in the workshop, the last before a price increase, and offered us one at a discount, which we accepted. We did not want to take the boat out of the water in mid season, so we arranged for Bursledon Marine to store our new engine until September, when we would bring the boat from Chichester Harbour to the Hamble for them to install it.

The boat was duly delivered in September and each Saturday we went down to see what progress had been made, and to take photographs. Graham the fitter knew that Yanmars had been installed in Corribees before, but when he first looked at Nyoni, sitting stripped down in their yard, he sucked his teeth and said it would be a tight fit. In fact it turned out to be easier than he thought, and fitted in very neatly.

The companionway steps were discarded, and the inner moulding floor was cut away in order to mount the engine bearers directly on to the hull. The humble engine bearers turned out to be a work of art. Weekly visits to the work in progress revealed at first two substantial balks of hardwood glassed to the hull. Subsequently these were finished to a state where the next stage appeared to be French polishing! On the following week we were puzzled to find they had become welt finished fibre glass beams. When Graham was asked why the wooden bearers had been so beautifully finished if they were then to be glassed over, .he replied, “Oh it would have showed otherwise”. He is a true craftsman.

Although the Yanmar fitted in to the Corribee more easily than had been expected, some compromise had to be made. One of the cockpit drain sea cocks had to be moved to make way for the exhaust. This was re-routed to the hull in way of the starboard keel.

As the engine intruded just beyond the space originally occupied by the companion way steps these were not replaced, and a substantial lift off wooden engine cover was made. This was lined with sound proofing material, and also functions as a step, a seat or an extra table!

Nyoni already possessed a comprehensive electric system, supplied by a battery in each keel, which had been charged in a half hearted manner by the outboard, and by a solar panel mounted on the lazaret hatch cover. The solar panel has been retained, and now feeds directly to the batteries via a two way switch. A heavy duty make-before-break battery selection switch feeds the charge from the engine alternator to one or both batteries, and also serves as an isolator. Although this belt and braces approach should ensure that power is always available to start the engine, it has proved possible (just) to hand start the engine.

The back of the skeg was cut away to make room for the propeller, which is positioned immediately forward of the rudder. When the skeg was cut in to, it was found to contain sand and lumps of concrete! Starting from inside the boat a passage was drilled down through the skeg towards the rudder, and a glass fibre tube was bonded in to provide for the drive shaft, at the same time massively restoring the structural integrity of the skeg. A two bladed propeller was selected after some debate. The argument in its favour was that it would provide for both more efficient motoring and sailing; the argument against was that it would cause a vibration. In the event the two blade was the right choice as the vibration and noise in the boat are less than that caused by the outboard, and experience has shown that when the motor is switched off and the boat is under sail the propeller free wheels until it has lined up behind the skeg, where it conveniently stalls and parks itself!

A five gallon diesel tank was installed in the aft lazaret on the starboard side against the forward bulkhead. This tank has fitted in very neatly, taking up far less space than the petrol cans it replaces, while giving sufficient range to motor to Cherbourg and back! The motor uses less than a pint of diesel per hour in normal conditions. A fuel filter and cock were also fitted in the lazaret.

Now that we have had a season with the Yanmar we can only say that we are delighted with it. The weight of the engine is in the right place, between the bilge keels, giving Nyoni excellent balance. She has ample power for any conditions we are likely to meet, and it is available at the touch of a button – no more leaning over the stern in a seaway struggling to start or re-fuel an outboard! There is no smell of diesel in the boat (something Kathleen was concerned about), and the boat handles beautifully, turning on a sixpence. The whole installation went well thanks to the professionalism of Marine Power, and although it was expensive we think it has prolonged the use of the boat for us.

Kathleen and David Bird, Winter 1996

***

Inboard engine installation

One of the members at my yacht club. Sean Harris, decided to replace the Vire in his Corribee with a second-hand Yanmar 10M (the original 6.5 hp version). I became involved, as I am a friend of Dennis Toms, the Marine Engineer Sean asked to fit the engine.

We looked long and hard at the best way to mount it and decided that, by strengthening the quarter berth sides we could dispense with conventional bearers and mount the unit on angle plates bolted through the berth sides. This of course greatly simplified installation. Dennis had already made the template for the relative positions of the shaft, feet etc. It was, of course, an enormous advantage having the old shaft and log to use In lining everything up.

Sean decided to try keeping the original propeller, I must say I had my doubts that this would be satisfactory but Dennis was willing to give it a try. The fuel tank remained in the lazerette locker aft, the exhaust was taken under the cockpit sole up into a swan-neck in the lazerette. A water-lock was fitted as low as possible behind the coupling.

Experience has shown the installation to be very successful, despite my misgivings about the prop. It is reasonably quiet and smooth running. Sean is naturally delighted.

Chris Austin, December 1999

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