[PCW] Outboards

[Bob Kupps]

Hello I had a 46' Wharram sailing cat with two four stroke 25hp hi thrust OBs.
   
  In addition to the advantages mentioned I would add lighter total machinery weight including the drive gear and fuel/parts compatible with dinghy motor.
   
  Much more significant disadvantages to the real ones already listed, IMO are:
   
  1) Total useful load for the same cruising performance would be difficult or impossible to safely carry.
  2) Reduced reliability
  3) Fumes are a real hazard that must be dealt with some vigilance.
  4) By far the most important problem will likely be prop cavitation. Even mounted on boxes which hinged down from under the cockpit seats, I frequently had to slow down to rediculously slow speeds when motoring into steep seas to avoid prop cavitation and the constant throttle handling (and noise) can get tiresome quickly even with an autopilot. 
   
  Naturally depending on one's intended use, and the pitching characteristics of a particular hull form,  these may be more or less significant
  

Gary Stavrou <gstavrou@bigpond.net.au> wrote:
  May I invite your general opinions on the subject of outboard engines.
It seems to me that for a light displacement cat of about 9-10.5m in 
length that a couple of outboard motors in the 60-90 HP range would 
be hard to beat.
The obvious advantages are:
1. Lower initial purchase and installation costs.
2. Cheaper maintenance.
3. Keeping fumes and vibration out of the hull proper.
4. Having more usable space in the hulls.
5. Better manoeverability at slower speeds.
6. Lifting the leg out of the water when moored.
7. Less risk of propeller damage.
8. Smoother, though higher revving, motors.

Other than having hot water without a gas setup, better electric 
power generation and that satisfying throb of a low-revving diesel I 
cant see why the outboards wouldn't be the sensible choice.
Gary
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