Twin Engine Catamarans, like their single engine counterparts, would greatly benefit from the installation of a Permatrim to work out their “quirks.” Most, if not all, twin engine Cats do not have the physical room on the transoms, next to the engines, to install trim tabs. If they do have hull-mounted trim tabs, they tend to be small in size and somewhat ineffective.
While underway in a twin engine Catamaran you may correct a weight imbalance by trimming one engine up or down for a port to starboard hull adjustment. These leans may be caused by uneven placement of people or gear on one side of the boat, or even being balanced improperly from the factory. Planing hull Cats have larger, heavier, 4-stroke outboard engines leading to high bow rise coming onto plane and they tend to fall off plane easily. Displacement hull Cats tend to lean out in turns at higher speeds. Since most do not have trim tabs, these boats tend to ride with the bow higher and cannot be trimmed down as much in larger head seas. With a Permatrim you will be able to trim down the bow which will allow the sharper bow hull deadrise to cut through the waves (instead of the flatter mid-ship deadrise) leading to a better ride.
I have sold new and used displacement Catamarans for several years. The particular line we sold came rigged with a cheap, plastic foil called a Doel Fin. From the beginning I doubted the effect these fins would have on a 26 ft. Catamaran. I did some testing and found that there was a slight improvement in fuel economy but that there were no other benefits and they were, in my opinion, an eyesore. I had sold one of these Catamarans to a customer and he absolutely refused the placement of the Doel Fin on his new engines. I was told, “I do not want those cheap-looking, pieces of garbage on my X$ new boat!” At that point I knew I needed to find a better foil. I did some research on the internet and came across a site called “The Hull Truth.” Through this site I began speaking with John Jensen, the USA distributor/outlet for Permatrims at the time. I agreed to do some testing for John on a couple of different sized Catamarans. In my testing I found that the Permatrims greatly improved fuel economy, created more sensitive trim reactions than the Doel Fins, decreased lean in turns, and increased speed by 1.5 mph at wide-open, trimmed-up throttle. The Permatrims also proved to be much more aesthetically pleasing installed on the engines than the other foils.
And the customer that would not let me install the Doel Fin on his new rig……he now has Permatrims installed and is a very satisfied Permatrim customer.