Engine & Energy Systems


Overview - Engine

Improbable has had three engines (that I know of). The original (I think a 3-cyl diesel) was first
replaced by dad soon after he got the boat, by a 1-cyl Volvo. Very low power but also low fuel
consumption, this was the same engine we had utilized for our 3-year cruise on the “Sara B”. So, dad
was familiar with the 1-cyl and trusted it. However, it wasn’t much power and was overwhelmed in a
headwind or pushing into rough waves. So, he eventually replaced it with a Yanmar 3JH2-TE, a 42hp
diesel that easily pushes the boat 8+kts.

Overview - Energy Systems

Sometimes fate deals me a surprising hand of cards. When we brought Improbable
to James Betts Enterprises (JBE) she was slotted into a spot right in the front of the facility, just inside
the fence along 34 th Ave in Anacortes. The JBE crew got the old rig and rigging out of the boat and laid down nearby next to another mast lying just along the fence. It turned out to be an old carbon Farr 40 mast, which is a fractional rig, and which happens to have nearly identical foretriangle dimensions to the original Improbable rig. The overall height of the Farr 40 rig is taller, allowing a bigger mainsail. This was very attractive, as the bigger main would pretty much eliminate the need for overlapping headsails, making for a much better shorthanding configuration with fewer headsails, faster tacking, etc. Jim managed to acquire the mast & spreaders from another project, and offered it to me at a very reasonable price. The changeover will save over 100lbs in the rigging overall…



Although Improbable was a racing boat, in my dad’s hands she became a high-performance cruiser. However, over the years the weight of the accumulated amenities kept adding up. He added a diesel generator, a diesel heater, kept the kerosene stove, added a lot of lead batteries, etc. The goal now is to get the weight lower than it has ever been (lighter than when launched in 1970) while having modernized amenities and a completely updated energy system. I want to race to Hawaii again and want to cruise to Alaska with a fully functional galley and have some level of amenities & privacy for guests.

Plan — Engine

We will add a high-power and high-efficiency American Power Systems (APS) 24V alternator. This will require converting the old single-pulley alternator belt and pulleys to a flat “serpentine” belt configuration. The pulley kit will be either a Balmar Altmount kit, or a Mark Grasser DC Solutions (MGDC) kit. The latter would have a higher pulley ratio (to spin the alternator faster) however will require moving the alternator forward somewhat.

Plan — Energy Systems

With a 24V (or possibly even 48V) system the recharging of the batteries is faster, and the conversion to AC (via inverter) is more efficient. Greater efficiency saves fuel, and the shorter recharge time makes life more pleasant. The galley will be all-electric, with an induction cooktop and a repurposed counter-top convention oven. Both will be installed in a gimballed box structure, run off 120Vac (as does a similar system in my home on land…so I know that it works!).

Challenges — Alternator

The MGDC pulley kit option has a better ratio, to spin the alternator faster relative to engine rpm. However, for the larger diameter crank pulley to clear an obstruction on the engine, the crank pulley, the water pump pulley, and the alternator all need to move forward. This may make fitting the APS HPI alternator difficult. At least there is a Balmar pulley kit option, it just doesn't have as good a ratio, so the engine must be at higher rpm for fast charging.

Challenges — Energy Systems

Mostly the main challenges will be finding the best locations for the batteries, inverter-chargers, possible small aircon/heating unit, etc. And…being able to pay for them!


May 2022…Balmar pulley kit acquired, otherwise all on hold until more done on the hull, deck, rudder, etc.