Scotty, We Need More Power!
Our first Prout Catamaran was a 37' Snowgoose. It had a single diesel engine with a long Z-drive leg sticking out the back of the center nacelle. The fuel economy of the 28hp Yanmar was phenomenal and speeds acceptable. We were looking for something similar but better in our current Prout Escale.
Having experienced mediocre engine installations in a number of monohulls, we wanted to keep engines out of living spaces. Hence, fumes and smells would be confined a completely separate space. Furthermore, the Z-drive was not intuitive to operate and we still managed to catch lobster pots. However, it was nice to be able to pull the pot almost out of the water to untangle it...
A twin engine setup would give us greater redundancy should one side of the system fail, we could turn on a dime, and driving was much like using the controls of a tank - easy. Twin engines also allow the use of proportional thrust - one side can push hard while the other just pulls a little. While Prout offered both single engine and dual engine Escales, we made the mistake of opting for a hybrid system based on hydraulics: Single-engine, dual propellers.
We came to this compromise at the end of a long and tortuous path. Initially, my father fantasized about water jet drives because they are pretty much immune to lobster pots, sand, etc. which is something you can find quite a bit of in Maine. But Prout was horrified. They'd never done anything like that, couldn't do anything like that. I suppose finding diesel-powered jet-drives in this size class might have been a further impediment.
Prout Catamarans refusal to install jet drives made my father turn to a hydraulic drive system where two independent circuits are powered by one engine. Prout Catamarans was not happy with this option, but it was a lot closer to what they were accustomed to. We hired a swiss marine hydraulics design firm called Diport AG to specify the system and Prout Catamarans installed it. Since then, Prout introduced the Panther series of powerboats - with jet drives, of course.
While the press is full of articles that make hydraulic propulsion systems look good in theory, there are some pretty good reasons why so few people actually use hydraulics for propulsion (bow thrusters for inept monohullers don't count). While our experience could have been better had the relevant parties been more competent, I still think that hydraulics (at least the ones I have experience with) are not as good an option as proper twin engine installations in multihulls. A single-engine hydraulic system is inherently more fragile, saves no weight, and is not as redundant as a dual engine set-up.
Our propulsion troubles start in the engine compartment where Prout Catamaran employees installed the only cockpit drain to empty on top of the engine instead of overboard. To compound our troubles, Prout had also neglected to install a drain into the engine compartment, so any leaks into the compartment would also drown whatever was in the compartment (like our engine, the starter, alternator, pumps, etc.). Then we discovered that Prout Catamarans installed a air supply to feed a 30hp engine, even though we have a 60hp engine in our Prout Escale. Our engine output suffered accordingly. That the fuel system was also installed incorrectly should not be too surprising by now.
Moving on, I lay out the hydraulic system as it was conceived, and how Diport AG, the people who designed it, bungled the specifications so badly that I wonder if the folks there had any idea how to design a marine propulsion system. Randomly picking components that fit together out of a catalog doesn't count. It did not take a lot of time to figure out the basic mistakes made by this company and the people who installed the hydraulic system into our boat. Most of the time was spent trying to fix the mistakes made by Diport AG and Prout Catamarans.
I also review the engine repairs we have had to make due to old age, spray-painting rubber hoses with engine paint, and other such nonsense. Lastly, I take a look at the idiotic mounting method used for our saildrives. There is no better way to catch lobster pots, damage the propeller, or destroy the saildrive than the "solution" that the combination of Prout Catamarans and Diport AG found.
Click on any of the following links to get a better understanding of what we had to deal with.
Best Estimate for Time Required to Remedy Propulsion Problems:
|Dealing with Leaks into the Engine Compartment||26 hours|
|De-constricting the air supply for our diesel engine||13.5 hours|
|Making the fuel delivery system work properly||10 hours|
|Introduction to the hydraulic design||42 hours|
|Issues with our hydraulic motors||49 hours|
|Issues with our hydraulic pumps||13 hours|
|Issues with our hydraulic reservoir and hoses||25 hours|
|Repairing the engine||62 hours|
|Fixing the raw water circuit||4.33 hours|
|Saildrive repairs||26 hours|