Preparing for the New Engine (I)

 The new engine for Wing has arrived.

 

 

It is a Beta Marine 14 which is almost twice the horsepower of the old Volvo Penta MD5A it replaces while coming in at about 89 kg rather than 111 kg.  It is a 2-cylinder engine with flexible mountings so I hope it will run more smoothly and be more quite than the old engine.

 

Fitting the new Beta will be an interesting exercise.  Although it is lighter the form factor is quite different.  In particular the new Beta has a heat exchanger rather than simple raw water cooling.  This makes the new engine taller and shifts the exhaust manifold both higher and further aft.  I have plenty of vertical clearance under the bridge deck but this space is only 18" or so fore-and-aft between the companionway ladder forward and the forward wall of the cockpit aft; there is quite limited space to play with!

To assist me in fitting the new engine I have made a plywood jig representing its external dimensions.  Below is the jig in place under the bridge deck.  The view is from the cabin looking aft towards the cockpit.  The forward wall of the cockpit can be seen covered with (very old) sound-proofing material below which can be seen the beam supporting the cockpit floor.

The engine just fits in the available space.  The top of the upright member on the right of the jig furthest from the viewer represents the top of the water outlet hose from the heat exchanger.  It is sitting right under the cockpit deck beam with about 1/16" to spare! Realistically I will probably need to hollow out a 1/2" channel in the beam to give the top of the outlet hose adequate clearance.  Given that there is a lot of structural support in this area such a small channel in the beam should not be a problem.  The four bolt heads represent the locations of the four engine feet.  The bolts themselves protrude through the plywood and I chose the length of the bolts to mimic where the base of the feet will land in relation to the rest of the engine.  I can use this information to modify the bedlogs.

 

Here is a view of the underside of the jig.  Again this is from the cabin looking aft.  The downward extension closest to the viewer represents the bottom of the oil pan while the more distant downward extension represents the gearbox.

 

As can be seen there is plenty of space under the engine so no problem there.  At the top left and right the ends of the two bolts representing the forward feet are visible.  It will be necessary to add inward extensions to the existing bedlogs for the feet to land on.  I hope to use some white oak for this purpose.

Behind the ersatz oil pan a large bronze plate is visible.  This plate is bolted to one of the floor timbers and was probably installed to provide extra support for the engine.  A more clear view of the plate is available when the jig is removed.

 

This plate is actually a bit of a problem because the aft feet of the new engine land exactly on top of it and I will need to cut about two inches off the top of each side of the plate to accommodate them.  Again there is lots of structure in this area and we are not dealing with a high-powered engine so I am not worried about any potential loss of strength but cutting the bronze in-situ will be messy and annoying.

Here is the aft end of the jig looking down through the hatch in the floor of the cockpit.  I have attached the flexible coupling to the back of the jig so that I can get the best match possible between the jig and the propeller shaft.

 

One of the things I have discovered from this exercise is that I will need a new propeller shaft coupling; the Beta 14 has a bolt circle of 3 1/4" while the old Volvo Penta coupling appears to have had a bolt circle about 1/16" smaller.  It is not a big difference but it is more than enough that the two won't fit together.  I have a lead on a coupling that should do the job and hopefully I will have it in hand soon.

Due to the new geometry the exhaust manifold for the new engine will land right in the access hatch in the bottom of the cockpit; I may actually need to raise the hatch a few inches to accommodate this.  I am also planning on having a 90° elbow added to the wet exhaust water injection port in order to both bring the height down slightly and to be able to lead the injection tube up to a siphon break.  This is necessary because despite its height the new manifold is still less than 12" above the load waterline.

As a result of this test I now have the following immediate tasks:

1. Cut the bronze plate down to accommodate the new engine feet.
2. Fabricate white oak bedlog extensions to receive the new feet.
3. Obtain a new shaft coupling.
4. Clean up the hull underneath and around the engine while it is accessible.

I hope to accomplish all these tasks in the next few weeks.