Wednesday, December 23, 2015

End of an era -- On to diesel power

After eight years of coaxing our old twin Chrysler Crowns along, we have finally made the decision to repower with diesel.  The Crowns are 6-cylinder, flat-head gasoline engines from the 1950s.  They have served us well (OK, pretty well), but it's time for them to go.  In their place will be brand new 80hp Yanmar diesels.  The work will be done at the Shipwright's Coop in Port Townsend, beginning the last week in January.  I'll do some of the work myself, and the guys from the Coop will do the "heavy lifting".
Our 2 new Yanmars waiting in Port Townsend.
The choice of new diesels for pleasure craft is pretty limited now, owing to recent air-pollution standards.  Gone are the days of simple, straight-forward, mechanical fuel injection in the U.S.  The only new engines available are those with electronic injection, which makes them overly expensive and unnecessarily complicated in my opinion.  I would much rather be able to troubleshoot a balky engine myself, which I can do with mechanical injection, than have to take the boat to a dealer for diagnostics, which is required with electronic injection.  But as I said, we have no choice if we wish to install new engines.  And what would be the point of installing used ones?

Volvo was another engine we considered.  I am told they are good engines, but support from the U.S. distributor is reportedly not as good as with Yanmar, and prices are about the same.  Engines from other manufacturers, including Perkins, Cummins, and John Deere, either were no longer sold in the U.S., were not available in the horsepower range we required, or were physically too large.  So we're going with Yanmar.  We had a 2-cylinder Yanmar in our Tartan-31 sailboat, and it gave us great service.  We had no problems whatsoever during our eight years of ownership, and I'm sure these will be the same. 

I swore when we owned the sailboat that I would never have a gasoline inboard engine, but as I explained in the first post of this blog, we decided Compadre was the boat for us, and gasoline is what we got.  The Crowns were rebuilt just before we bought the boat, and only had 11 hours on them.  They're about ready to turn over 1200 hours, but the engines themselves are very rugged and have a lot of life left in them.  The problem has been all the ancillary equipment (carburetors, fuel pumps, distributors, coils, etc.)

Compadre's Twin Chrysler Crowns
Fuel pumps have been particularly annoying.  They are not original, of course, since the engines are at least 60 years old.  These are after-market pumps, more-or-less the same as the originals, but with some short cuts.  It's the short cuts that give you fits when you are miles from home and suddenly an engine stops.  They have failed so many times that whenever an engine stops, Cindy asks "is the fuel pump pin in place?"  That would be the steel pin about which the pump arm rotates.  In the original pumps it was held in place by 2 retaining clips, but in the modern replacement it is simply pressed in in the pump body with the hope that is will stay (it doesn't).  After a few hours it works loose and backs out of the pump body until it looses contact with the pump arm, and everything comes to a halt.  I've tried various fixes, but the best one is simply to span the pump pin with a small c-clamp, thus keeping it from moving.  Not elegant, but fool proof.  We've cruised for two years with that c-clamp in place and had no further problems.

We've had no end of trouble with carburetors.  But to be fair, at least some of the problems are more the result of  modern gasoline formulation than the carbs themselves.  Modern gas is more volatile than it was when these carbs were designed, which poses a particular problem when you try to restart the engines after they've run for an hour or so.  If you are lucky, they'll start right back up.  More likely than not, however, one will refuse to start until the engine cools down, which is a real problem if you have shut down the engines at the fuel dock or in the Ballard Locks and now want to get under way again.  Too many times we've had to limp away on one engine, hoping that we could get back to where we needed to go.

And the carburetor on the port engine is simply not right.  It floods every once in a while for no apparent reason, but invariably it's when we are about to leave on an outing with guests aboard -- just refuses to fire, large amounts of fuel coming out the exhaust, and nothing you can do except pull the thing off and tear it down.  I've had both carbs rebuilt professionally, and was assured both were OK.  But they're not.

So all of this will soon be in the past.  The Yanmars will be more reliable, more economical, and much safer.  So why did it take so long to come to this decision?  In a word... money.  This project will cost nearly as much as we paid for Compadre back in 2007.  But we knew the gas engines would eventually have to go, so better to replace them now and get some use out of them than to wait until we are thinking about selling and have future owners reap all the benefits.  Such is the nature of classic boat ownership.

One knows going in, or should know, that the purchase price of these classic boats is low for a reason:  Much of the long-term expense of ownership is out in the future somewhere, unlike a new fiberglass boat where most of the expense is up front.  I will have much more to say about this in a future post, as it is perhaps the most important thing to understand about classic boat ownership.  Classics are not more expensive to own than new fiberglass boats -- the expenses just come at different times.

It will be interesting to see how the engine swap affects Compadre's performance.  With the Crowns we cruise comfortably at 8 kts with the engines running at only 1500 rpm.  At that point they are putting out about 60 hp each, according to the power curves published in the Chrysler maintenance manual.  The Yanmars are rated at 80 hp at about 2800 rpm if I remember correctly.  The torque curves are different, of course, with the Chryslers reaching max torque at a much lower rpm than the Yanmars.  So we'll have to see.  I'm sure we'll have to do some prop adjustment to get things right.

However it works out, we are not likely to match Compadre's performance when she was new.  She was originally equipped with twin 6-cylinder Lathrop Mystic engines, which were enormous by today's standards.  They weighed in at 1700 lbs!  That compares with 800 lbs for the Crowns, and 500 lbs for the Yanmars.  The Lathrops were quite sophisticated for their time, with two spark plugs per cylinder.  They were rated at 100 hp at 1800 rpm.  The Lathrop engines were options offered by Stephens Brothers; the standard engines were Scripps model F-6, 100 hp.

6-cylinder Lathrop "Mystic" engine, from 1929 Lathrop catalog.
In any event, Compadre's original performance must have been impressive.  Advertisements from Stephens Bros for their 43-ft cruisers claimed maximum speeds of "18 to 25 miles per hour", which surely was overstated for a displacement hull of this length.  We have no written documentation of her performance, but in this early photo of her in the San Joaquin Delta she clearly was moving right along.
Early photo of Compadre in the Delta.  Possibly sea trials in April 1929.
 Notice how far the bow is out of the water and the size of the wake.  Now compare this with a recent  photo of Compadre running at 8 kts.
Underway at 8 knots in Brentood Bay, B.C.
There's no doubt she was moving that day in the Delta.  I only wish I knew the details!  We'll be posting details of the repowering project after it gets started.  Be sure to check back.

No comments:

Post a Comment