93' Diablo 180 outboard engine 150 HP porpoising
 

Hi All,

I've recently entered into the world of speed boating with a Diablo 180. Overall it is a great handling boat, even took it out on a 4 scale Beaufort and it handled the waves well.

I'm having a bit of an issue with the fuel consumption its close to 2 liters per nautical mile probably due to allot of porposing at cruising speed of 25-30 knots at 3000 rpm and that forces me to trim the engine down almost to the 3/4 to all the way depending on the chop of the open sea (reduces my consumption a bit and stops porpoising). Also noticed that that it will max out at 4000rpm and I'm thinking of trying a different propeller maybe a high five to see if the extra blades help the engine open up more.

Re: 93' Diablo 180 outboard engine 150 HP porpoising
 

I'm not overly familiar with your boat, but have you considered installing smart-tabs to help level it out?

Re: 93' Diablo 180 outboard engine 150 HP porpoising
 

Hi GregT,

Probably will install tabs , just doing some research but will probably go for the hydraulic or air system ones.
Now im thinking of swapping 3 blade 21p with a five blade 21p to see if I can plane better without having to down all the way the engine.

Re: 93' Diablo 180 outboard engine 150 HP porpoising
 

You dont need hydraulic or electric trim tabs on a 180. Just install a pair of Nauticus Smart Tabs with the 60# arms and they will do the job. A 3 blade 21" pitch prop is a 'cruising' prop for those boats. A 5 blade will help but dropping to a 4 blade 19" pitch and a pair of Smart Tabs will have your boat jumping out of the hole and also improve your mid range acceleration at the cost of about 2 mph top speed. That's a good trade-off in my books.