Case Study:
Humphree Interceptors

A flat and comfortable ride is a priority for enjoying time out on the water, but sometimes it doesn’t quite come together. But there are solutions, and ovlov marine has recently been involved in several projects where Humphree Interceptor Systems have been retro-fitted to improve performance and fuel economy.

The recent projects, from a classic 1980s launch up to a mini-superyacht, have illustrated how installing new Interceptor trim tabs can make a huge difference to the boat’s performance — and therefore her owner’s enjoyment.

“For semi-planing and planing boats, Interceptor-based stabilisation systems reduce roll and pitch motions, improve performance, reduce fuel consumption and provide more comfortable turning,” Matt Jackson of Ovlov says. “Interceptors are like a trim tab, but instead of a conventional tab with a blade that folds down, these are units mounted vertically on the transom with a smaller blade driven by an electric motor, which provides rapid and precise adjustment.”

Once fitted, the system is carefully calibrated to the individual vessel, then basically runs itself. No further adjustment is required, but the system can be manually overridden if required.

One of the projects was a 16-year-old, 27m Johnson motor yacht, recently imported from the United States. The hydraulics in the conventional blade trim tabs needed replacement, but when that was priced up, it wasn’t going to cost a lot more to replace the tabs entirely with a Humphree Interceptor system – and improve the boat’s performance at the same time, Jackson says. The Humphree units for this boat are 1500mm long, and can be paired with Humphree electronically-controlled fin stablisers.

“With this boat, the owners also wanted auto-stablisation, so we went for the Humphree auto-list function, which provides list and trim control all in one easy-to-use system,” Jackson says.

“We’ve had some really impressive results — we’ve corrected the trim by 1.5o, which might not sound like much but it’s the difference between seeing over the bow and not, especially from

the main bridge.

“It’s also changed the wake of the boat quite dramatically, to produce less wake and disturbance, especially at cruising speed.”

Ovlov has also fitted the system to smaller craft, including 1980s-era Salthouse Corsair Mark II, and a 21m Maritimo based at Opua in the Bay of Islands.

“With the Corsair, the owners wanted a better ride quality, and because the boat has quite a wide aft section, she was getting pushed around in a following sea,” Jackson says. “The Humphree Interceptor system has pretty much corrected that.”