Outboard Transom Angles??

[Bullshipper]

I am looking for the recommended hull transom angle for Yamaha outboards 115-225hp, and find nothing when I look at the oem's stuff or google.

I assumed it was about 14 degrees on a boat that rides level (catamarans), and about 11 degrees on monohulls with a 3 % keel rise when going slow.

Can anyone help me out?

[gonzo]

14 degress is the nominal dimension. However, that means it gives you enough to trim the engine in for better hole shot, and then you should trim out as the boat planes.

[hmattos]

Here at Explorer Marine - www.explorermarine.co.uk - we used to build to 12 degrees in the 1990s, but as engine hp has increased and tilt and trim systems have improved, we have now moved to 15 degrees where the engine is mounted and then extend the planing surface back to improve handling and minimise bow lift.
We usually fit 115 - 150+ hp Evinrude ETEC or Suzuki DF on RIBS from 4.5 to 10 metres.

Hope this helps
Hugh Mattos

[Bullshipper]

Thank you both very much.

The boat I am designing needs to back down well for large fish species, so I think I will try 16 degrees on the prototype, realizing that these motors have more range tilting up than down