Tsunami – High speed hydrofoil based on the OU32

Tsumani – a fast tandem dual leg hydrofoil powered by a shrouded 30 HP outboard motor

The original OU32 designed by Yamaha’s Kotaro Horiuchi in 1987, shown as relaunched in 2020

Year three into a four-year project to produce a garage built version of Kotario Horuichi’s OU32, as outlined in the Jan 2022 IHS newsletter, I can report that progress has been steady. The canopy is fitted and functioning, and the upholstery and internal furnishings are fitted. The front foil, which retracts into the boat, has been fitting and the retraction method is conceptualized and fabricated. The mechanical components for directional and pitch control for both the front foil and vertical stem, and the 30 HP outboard motor have been installed, but the electrical portion of the control system (servos and controllers) has yet to be completed.

Progress is pleasing but the canopy did not go as planned. I have used 3mm acrylic  and found it difficult to “blow” without a large oven, so have settled for a less aesthetic two dimension curve.  I may try again using 2mm acrylic sheet.

Some colour stripes are to be added over the white basecoat for appearance, and the boat has yet to be seated on a trailer.  The boat is currently slung from the overhead garage beams to allow the front fin to be fitted from below. It doesn’t quite clear the canopy to allow for installing from above. Perhaps a design oversight!

Above- the front foil partially retracted for shallow water operation. Also, the bearing through which the front foil passes. This carries the weight and load of the boat when on the foil. Image three is the dash and seats trial fitted.

Below, the cad drawing on which the boat hull is based- build with West System stitch and glue technique using 6mm ply and 250 gm weight glass cloth to exterior surface.

The is a project I decided to invest in after retiring in 2020. Something with a lot of complexity and a bit of brain challenge. I have another project rumbling along for the past 10 years – and aquabike driven by pedal power and no flotation. It has not yet succumbed to success, so lets hope this project has a better outcome.

More photos to follow:

My 10 year project – the Aquabike, at Lake Tarawera, NZ. I would be delighted if anybody could let me how to best launch it for the maiden “flight”.
Clamping the canopy forward bracing structure as a ply/ fibreglass composite.
Trial motor installation. This is a 30HP 4 stroke mercury that is shrouded/ enclosed and is yet to have a 400mm shaft and housing extension fabricated and fitted.

Below is the complicated mechanism to control the pitch of the front fin, via a rod passing down through the vertical fin, using paired R/C servos. These have a rapid response to control inputs and are rated at 35Kg – so should do the trick!

There is also a car windscreen wiper motor set up to withdraw the vertical fin into the boat – for shallow water maneuvering.