Diesel Installation in Yankee 30 "Tootsie"

Buying myself a problem.

I purchased my Yankee 30 in May 2002 quite by accident. The Yankee was a smaller boat than I had had in mind, nor had I planned to buy a boat just then. But there it was, very seriously for sale, and I have always had a soft spot for this little yacht.

Ed Basham had owned the boat and lavished care on it for about two or three years before I bought it. Then the Atomic 4 engine got saltwater into it when Ed kept cranking the starter and the engine wouldn’t fire. I had never considered this possibility, but there you are. Keep on cranking and the saltwater pump will keep pumping water through your motor until it fills your exhaust and backs up into the engine.

The problem that had now become mine is one that a lot of owners of otherwise fully functional older sailboats with fading Atomic engines are facing. Undoubtedly the simplest solution would have been to repair the damaged Atomic or find a reconditioned replacement. However, I have witnessed the horrendous explosive power of gasoline fumes up close. I have struggled with carburetors and with the varied electrical problems of gas engines and I will not live with a gasoline inboard engine again in any boat of mine.

The three aspects of the Yankee 30 diesel installation dilemma.

The Atomic engine is very narrow towards the bilges and uses a very narrow engine bed. Modern diesel engines with the flywheel facing aft are wider down low and require a wider engine bed and more sideways clearance in the bilges. Fitting such an engine in the limited space available under the settee in the Yankee is next to impossible without boat surgery and taking away from the interior of the yacht.

In a lot of cases, including the Yankee, the Atomic used a direct drive, swinging a small propeller at high revs. Thus, the second problem has to do with the limited space dedicated for the propeller with the high revving Atomic as new diesels are geared down to swing a large prop at less turns.

In the Yankee 30 the prop is limited to 12” diameter without extending the shaft and installing a strut and bearing on the hull to get more clearance. Even the 12” prop is pushing the limit considerably beyond what is standard accepted minimum clearance to the hull above (15% of prop diameter).   The real power to push a boat against chop and wind is directly proportionate to propeller diameter. Using a small, high pitched prop at very high revs on a displacement boat becomes a bit like trying to paddle with a teaspoon. No matter how furiously you paddle there is not much power generated. The trouble is you can’t fit the ideal prop for the slower turning shaft of your new diesel.

The third problem has to do with the economic aspect of the diesel equation. What is it going to cost to get a diesel installed and what is the value added by the effort? Is it worth going through the exercise?

Analyzing the problem.

A good beginning is to ascertain what would be the appropriate diesel engine for a sailing sloop of 23’ LWL and approximately 9000 lbs displacement? The answer provided by experts and tables seems to be about 16-18 hp. The questions you have to ask yourself then are:

A: Is there an engine in this size range that will fit in the designated space in the Yankee 30 without requiring excessively costly modifications and butchering the interior of the boat? The answer to this question is very likely no, unless you go through the contortions described further on.

B: Assuming that you somehow manage to fit a diesel of about 18 hp, will you be able to swing the ideal prop for this engine, hull and displacement? The answer to this is definitely no, unless you install a strut aft of the keel and extend the prop shaft so that you get clearance for a 14-16” diameter prop.

C: After so many years around boats and in the marine industry I realize that boat ownership is not governed by laws of common sense and logic. If your Yankee is the love of your life and you wouldn’t trade her for anything you just have to bite the bullet. However, unless you are blindly in love and oblivious to what your investments in your boat will one day return, you have to ask yourself what is reasonable for you to spend on getting diesel power installed.

If you just open your wallet and ask for a diesel you will be paying around $6,000 for your new engine. The installation is going to cost you another $6,000 or so, if you don’t want to get heavily involved yourself. No kidding! This is the truth once you rack up haul-out, new propeller, shaft and coupling, strut installation, electrical and fuel system, exhaust and engine bed modifications and so on. So what will a decent Yankee 30 fetch with a diesel installed? My guess is that it will sell for about $15,000 to 20,000. What will it fetch with a working old Atomic in it? My guess $8,000-12,000. With a new diesel installation worth more than the boat itself it is no wonder the old Atomics get babied along by their owners.

Buying a small diesel for TOOTSIE.

I have already stated my opinion of inboard gasoline engines. Therefore I really did not have a choice as I wanted an inboard engine for cruising. Nor did I want to overcapitalize my investment in the boat, so I was prepared to look around for a deal and do the installation myself.

Looking at new engines I contemplated the two cylinder Yanmar, the 11 and 13 hp Vetus and the 10 and 13 hp Beta Marine diesels.

It would have been nice to have a Yanmar, but the market leadership of that engine keeps its price firmly at the $6,000 level. I know people have installed them in the Yankee but, after crawling around the bilges for hours with a tape measure, I could not figure out how, without botching the boat.

The small Vetus engines are based on Mitsubishi diesels. I was offered a substantial discount from the company back East and would have avoided sales tax, but these engines were wider than any other down low, almost 20” at the mounting pads, and simply would not fit, though I loved the price. (I have since discovered, reading “What they say about the Yankee 30” on the Yankee website, that a Vetus diesel was installed in a Yankee by Bob Rabe. I would love to know what changes it required.)

Beta Marine small diesels are based on Kubota engine blocks. I could get a discount, but nothing on the order of what Vetus offered.   These engines are advertised as replacements for the Atomic as they can be delivered with narrow mounts to match the dimensions of the Atomic on the engine bed. However, exercises with the tape measure indicated that these engines were too high (so you would have to sacrifice the settee), and it appeared likely that the oil sump might run up against the hull (so you could not properly align the engine with the shaft).

I kept my eyes open for a used diesel, but only half-heartedly. Mostly, they are for sale for a reason you would not like, if you knew it. The few I found did not inspire confidence.

Then I decided to check if maybe there was something for sale on Ebay. Lo and behold, someone with an aborted boat building project in Grants Pass, Oregon, was advertising a 10 hp Nanni Marine diesel, never used. Looking at the internet (nannidiesel.com) and talking to people in the industry I discovered that Nanni is a French company. Though they are quite well represented in other parts of the world they had only made a spotty effort at selling in the US many years ago. The smaller engines are based on the same Kubota tractor engines used by Universal, Westerbeke and Beta Marine. This ought to be a good engine.

So, what about only 10 hp? I, for one, felt that it would do me just fine. When I sailed around the world in my 14 ton, 40 foot cutter in the early seventies we replaced the dying 60 hp Gray Marine gas engine in Tahiti with a 25 hp MD2 Volvo diesel. With a suitable prop this engine cruised without straining, in calm waters, at 5.5 knots, using only 1/3 gallon of diesel per hour. If needed it could be made to go at well over 6 knots.

If a 25 hp diesel could do this on a 40’, 14 ton(!) yacht with a 59’ mast, shouldn’t a 10 hp diesel engine be adequate for a Yankee 30 with only 9,000 lbs displacement? I am sure the answer is yes and that a lot of sailboats are vastly overpowered. The only time their great engines would ever pay for themselves is if you were towing - or you were trying to power against a gale in the open sea. But then, why would you ever attempt to do that as long as your mast and sails are at hand? You would be sailing, or perhaps motor-sailing, and all the extra horse powers are nearly always superfluous.

Furthermore, with the limited space available in the Yankee the smaller size of a 10 hp engine, weighing less than 200 lbs ought to be a definite advantage.

I decided to buy this engine and then deal with whatever installation problems it generated as best I could. However, I had not counted on the difficulties presented by the owner of the little diesel. Twice I became the winning bidder for the Nanni, but he refused to sell it to me as the bidding had not reached his unrealistic expectations. In the end I drove up to Grants Pass and finally struck a deal at a good deal more than I had wanted to pay.

Installing the Nanni.

By this time I had studied the description given by Bill Ramelli of the diesel installation in his Yankee, using the CV (constant velocity) joints out of a car to be able to offset the engine to the propeller shaft and thereby make it fit it in the existing space. My Nanni could probably have been hooked up directly to the shaft with some surgery on the settee but I was sold, perhaps “seduced” is more fitting, after seeing Bill’s description on the Yankee website. As Bill’s method is the one I also used, my discussion will focus on the differences between my own installation and Bill’s. I will also try to go into some detail on problems that are not mentioned or explained in Bill’s account. Therefore it would be a good idea for anyone interested to first go over his description. (Go to ANDIAMO in the owners’ register on the site. Click on it and it will take you onwards to Bill’s description).

Engine Bed.

Bill’s Yanmar and my Nanni have quite a different lay-out. The Nanni has the exhaust coming off the port side of the engine. The aft mounting pads carry hardly any weight at all and are positioned all the way aft of the gearbox. These two factors forced the engine further forward towards the bulkhead in order to be able to turn the exhaust over to the starboard side and to fit the aft mounts inside the settee space. The one clear disadvantage of this is that I only have a couple of inches clearance to the bulkhead forward of the salt water pump and changing impellers is not going to be much fun. An advantage is that I have more space between the gearbox and the shaft stuffing box to fit my flexible shaft connection and the thrust bearing and its mounting plate.

The mounts on the Nanni are considerably higher up than on the Yanmar. This allowed me to go away from Bill’s method with a threaded stainless metal strip almost on the hull on the port side. I had enough clearance below the port mounts for a glassed over wood bed, allowing me to use lag screws of at least 3” length to bolt down the mounts, without touching the hull.. On the starboard side I ended up discarding the old stainless Atomic bracket and using a bolted and glassed over wood bed on this side also.

Exhaust System.

Because Bill’s Yanmar is deeper down in the bilge he had to build his own shallow profile waterlock to fit under the engine. The Nanni Kubota block has a small oil sump forward that is quite deep, but I was able to fit a standard Vetus waterlock just under the gearbox and aft part of the engine and strap it to the engine bed on the starboard side. Its bottom rests on four keel-bolts at each bottom corner, which allows bilge-water to flow freely underneath as well as to the side of it. I reinforced the waterlock where it rests on the bolts with fiberglass spackle in case it should vibrate and wear but all the vibration is taken up by the flexible exhaust hose and the waterlock appears not to move at all.

The hose connected to the outlet side of the waterlock is also strapped to the starboard side engine bed and then enters the head, where it joins up with the old Atomic exhaust, at the bottom of the bulkhead by the stainless tie-down strap. Bill has fashioned a connection through the bulkhead using copper pipe fittings, but I have always been told not to use copper in a diesel exhaust system as it supposedly gets chemically attacked by the high sulfuric content of diesel exhaust gases.

CV-joints.

Using the constant velocity joints from a car to be able to mount the engine where it fit, without having to line it up with the prop shaft seemed like a brilliant idea. However, I have to confess that before I was done with it I had my moments of severe frustration.

After visiting a number of junk yards without finding anything that looked remotely like Bill’s tidy connection, I had to call him and found out that the joint he had used came out of a VW Vanagon. This is the one you have to look for as it has a flat, about 4” dia connecting surface that can be adapted to your couplings at either end. I finally located a VW scrap place and bought three complete CV joint axles for a total $75 (you only need one, but I was so glad to find them I couldn’t help myself).

In order to adapt these ends to your shaft and gearbox couplings you have to have two intermediate adaptor plates made up, one with holes drilled and tapped for the six bolts of the CV joint end and the four bolts of the gear box coupling forward and one tapped for the three bolts of the Atomic shaft coupling aft. I bought a piece of 4’ round stock aluminum at a scrap metal place and had two 3/4’ thick adaptors turned and tapped from it to fit between the CV joint and the engine coupling and the CV joint and the shaft coupling.

Shortening the CV axle.

The CV joint assembly that you buy from the scrap yard has a flexible ball bearing joint at either end mounted on a steel connecting shaft. This shaft is too long to fit in the limited space available in the Yankee. I imagined that I would cut it and then have it re-welded to a shorter length. This is indeed what Bill said he had done when I had to phone him again. It turned out no machine shop wanted to touch the project as the shaft was hardened steel and the welders felt that they could not guarantee making it straight after re-welding. In desperation I walked into a gear cutting shop where the nice owner cut me a new, shorter, stainless steel shaft and machined the splines and lock ring groves to hold the joints at either end and also machined my adaptor plates, all for $120 and a six-pack.

Degree to which engine and shaft should be offset using CV-joints.

It would seem that you should strive to get your engine as near as possible aligned with the propeller shaft and that this would cause the least strain and wear. I was informed otherwise by Bill Hickman, a naval architect who had worked with CV-joints in different engineering projects. Bill told me that CV-joints should work at least through a 5 degree angle. This surprised me at first but when you look at the joints you begin to understand why. These are not fixed ball races. The balls run in channels which allow the joint to flex. If the alignment is near perfect it means that the balls remain working at one stationary location in their channels, which produces excessive wear and deterioration.

Thrust bearings.

The next frustration involved finding a thrust bearing to fit my 7/8” prop shaft. Again nothing could be turned up that looked remotely like Bill Ramelli’s installation. I had to call the poor man again, but he remained steadfastly kind.

What I got out of this conversation was that perhaps Bill’s bearing was not a thrust bearing but a bearing that could take thrust. As it turns out regular aligning bearings can take quite a bit of thrust and should be able to handle the forces generated by a small diesel and its propeller. As I did not feel totally confident about this I decided to install one bearing on either side of the bearing plate. This also gave me added confidence in that I now had a total of four set screws instead of just two keeping the shaft in place and locked to the bearings.

The mounted bearings I ended up using are Hub City FB260X7/8 at about $20 a piece after I got a discount. At about 1000 shaft rpm this bearing can take about 800 lbs of sideways load and 25% of that number in thrust. As I have two bearings they should be doubling the allowable thrust to somewhere around 400 lbs, which should be well within the limits of the thrust that my engine and prop can develop.

Bearing plate.

I made up a thin plywood template for the bearing plate. I then had it cut from a piece of 1/4” corten steel I happened to have, including the hole for the shaft and the bolt holes for the bearings. Bill mounted his plate by glassing metal straps to the hull with ears for bolting on the plate. I chose instead to have straps welded on to the plate – two each side going forward and two each side going aft. I mounted the bearings on the plate and slid the assembly onto the propeller shaft. I had made up a wood contraption to hold the forward end of the shaft in alignment while I positioned the plate with the bearings mounted where I wanted it and filled the voids between the straps and the hull with fiberglass spackle. I then glassed the straps to the hull after the spackle had set.

I have a hunch that my method was marginally easier than Bill’s, but I can’t take my plate out, if I ever wanted to, without cutting away the fiberglass. If done my way it is also essential to have enough clearance between the aft bearing and the stuffing box so that the prop shaft can be slid aft, clear of the aft bearing, without the keyway entering the stuffing box and producing a leak. Otherwise you won’t be able to change the aft bearing in the water, if ever required.

The bearing plate with welded on straps glassed to the hull fore and aft either side. One bearing is mounted on either side of the plate. There is enough clearance between the aft bearing and the stuffing box to be able to slide the shaft clear of the bearing, if it has to be replaced, without causing a leak from the keyway entering the stuffing box.

Other installation projects.

The above descriptions are specific to the “Ramelli” CV-joint method. I also had to deal with the problems of any gas to diesel conversion: cleaning the gas tank, installing a fuel return line and a diesel fuel filter, adapting control cables and the fuel strangling cable necessary to shut off a diesel, mount the instrument panel etc. These are fairly straightforward issues. The panel itself ended up mounted on the flat surface behind the engine controls in the hollow space to port in the cockpit where it is well protected.

Test run and evaluation.

The engine I had bought was “new” but had been sitting on the floor of a workshop for more than ten years. I had my fears throughout that something might be wrong with it after all that time and that all my efforts would be for naught,

I got a good tip from my friend Cree, the owner of Berkeley Marine Center. He claimed that he always used straight automatic transmission fluid when starting up engines that had been sitting for a long time. Modern diesel fuel is almost too clean and doesn’t lubricate like the AT fluid, which frees up injector pump mechanisms etc. AT fluid also has the property to emulsify water droplets and render them harmless to the injector nozzles. Beginning its life on a diet of automatic transmission fluid my little beast fired up right away and started purring like a kitten. Everything is working perfectly, including the shaft linkage.

I am sure I have managed to convey that this project had me frazzled from time to time, but in the end it was all worth it and an education. If I have any lingering reservation it has to do with the fact that open bearings are required in a bilge that has a very limited capacity to hold seawater. In a big storm it appears likely that the bearings would get dunked. For this reason I have acquired two spare spare insert bearings before I do any extended cruising All in all I am very happy with the installation and if I ever should have to change engines again the existing CV joint arrangement should make the project easy.

Engine tucked in and resting peacefully in the designated space after months of toil and head-scratching.

Propeller problem.

My Nanni has a Hurth HBW 50 gearbox. The standard forward gear has a reduction of 2.72:1 with a standard reverse of 2.15:1. I have been told that you can reverse the gears and use a left-handed prop, making the reverse gear the forward gear at the 2.15:1 ratio. The engine is rated at max 3,600 revs.

This means that at a working speed of around 2,700 revs (75% of max) I will be getting about 1,000 shaft rpm, which is less than half of what the old Atomic delivered. Using the same two-bladed 12x7 prop I would be getting nowhere and under-loading the diesel, which needs to be working at the designed load.

Bill Ramelli started out with a 12x12 three bladed propeller for his new installation, but got frustrated by its lack of efficiency and has since installed a longer shaft and a strut and
a 14” diameter prop, which gives him much better performance. He has been kind enough to lend me the old 12x12 prop for trials.

I am hoping against odds to be able to avoid the cost and trouble of having to go to a strut. My engine is considerably smaller than Bill’s and will not swing a very large propeller anyway. It does turn the 12x12 in forward (ratio 2.72:1) reaching what appears like full revs without trouble. However, in reverse (ratio 2.15:1) I can’t get the engine to rev up and it smokes and is clearly over-taxed.

Neither am I very happy with the “bite” the prop delivers in forward. I can reach about 5.5 knots in flat waters, but the prop seems to be slipping a lot. Getting out of the blocks when you shift into forward from stationary takes far longer than I like. I have a feeling that the inadequate clearance of the prop to the hull and the keel just in front of it do not provide enough clean water for the prop to work well in forward, making it slip and cavitate. Perhaps this, and not just the more favorable gear ratio, is the reason why the engine has no trouble revving up to max in forward gear.

Obviously I am not finished with this side of the diesel conversion. I have not given up on improving performance without a strut, but it may have to come to that in the end as there is simply very little clearance for a decent prop with the standard Yankee arrangement.

Finally, I end this lengthy discussion with the hope that it will be helpful to some other Yankee sailors. Good luck to you all!

PS: I have since solved the propeller problem by using a "wing tipped" 12x9 prop from Bay Propeller in Alameda. Amazing results. I cruise at 5.5 knots at half throttle or less with a 10 hp engine!!! Big sacrifice in reverse though.

AAlso I have had to remove one of my double thrust bearings. Clamping them together caused over-heating. This made it necessary to consult a naval architect friend about the actual thrust created by a 10 hp engine on a 9000 lbs hull. Not much it turns out. Max about 180 lbs at maximum resistance from wind and waves. One bearing is all that should be used.

Would I do this again? Probably not. -Carl

DIESEL INSTALLATION IN YANKEE 30 “TOOTSIE”