Ocean Alexander 423

[Captainpete12]

I am purchasing an OA 423 and will be bringing it up the AICW from Florida to New York. I am having difficulty finding out fuel consumption on the Cat 3208 NA. If I run at 1500 rpm giving me about 8 knots what should I expect for fuel consumption/hour on each engine or for both. Thanks for any feedback.

Capt. Pete

 

[Comodave]

Congrats on the new boat. Haven’t had those engines but I would guess around 8 to 10GPH at that speed.

 

[Flatswing]

Sounds like you are on a “delivery schedule” so at 8 knots Comodave’s estimate is probably accurate. Along the AICW, some days you will be running against the tidal current and burn a lot more fuel and at higher rpm. Other days, the tides work in your favor.
Your new OA, like many trawlers/ cruisers is rather inefficient if you are running at or near theoretical “hull speed”. If fuel burn is important to you, slowing to 6-7 knots will reduce your fuel burn significantly.

 

[mvweebles]

Hull speed is the speed at which the boat starts to climb out of the water on to plane. It's a mathmatical formula described as 1.34 x squareroot of the waterline. Assuming your OA 423 has a waterline of 38-feet, that works out to 8-1/4 knots or so. As Comodave notes, I would expect fuel consumption to be at least 8 gal/hr (efficiency of 1 gal/mile). Drop the speed to around SL = 1.1-1.2 (approx 7-knots), and the efficiency should improve by 15%-20% - around 0.8 gal/mile. In real terms, over the course of 1000 mile trip, you'll consume 200 fewer gals of diesel and save around $800. It will take an extra 17 engine hours (142 @ 7 kts vs125 @ 8 kts), which could be an extra 2-days so a chunk of the $800 may go to marina fees and a couple nice dinners which sounds like a better use of money to me.

I love trip logs - hope you post your adventures. Best success-

Peter

 

[Flatswing]

Peter’s numbers are correct especially for hull shapes like his Willard, KK’s etc. Other hulls like my DeFever and the OA under discussion, unfortunately aren’t that efficient, probably need at least 1.5 knot reduction from theoretical to reduce the stern squat & bow wave ime.

 

[Osprey69]

We have 3208s and displace 44,000 pounds. We cruise at 1400 RPMs (8.5 knots) and have seen 5 - 6 gals an hour while also running the generator for a time every day.

 

[RickyD]

I have a 66,000 lb 55' with Cat 3208TAs and get 1 mile per gallon at 10 knots and 1750 rpm. I actually average lower consumption of 7.77 gallons per run hour because of time running at idle, 5 knots in the harbor, and anchoring etc.

 

[Captainpete12]

I appreciate the feedback. I am going to try to run outside weather permitting at least from Jacksonville to South Carolina and then again from Cape May to New York.

Capt.Pete