Hatt 36 70 Mile Total Range!!

[CA36]

Just ran my fairly new to me 1969 Hatteras 36c (with Chris Craft 427's) for 52 miles at 2600 rpm (10 knots) and burned 180 gallons!!!! That equates to a total range when topped off of around 70 miles. Is there something wrong or was i a uninformed fool to buy this boat/engine combo???????

[saltshaker]

Something is not right. If your info is right, you are burning 33gph at that speed. I had a 36Trojan with 460s that would burn about 32gph at 3200rpm and 22 knots. I would think your Hatt should burn the same but run a bit slower like 16-18kts

[mike]

FWIW, from your description the boat never got on plane. Calculated hull speed for a 36’ boat is in the 7-8 knot range (sqrt of waterline length @~ 33' = 5.74 * 1.34 = 7.7 knots). To take advantage of your hull design and maximize fuel efficiency you need to get out of the “hole” and get on plane, which is well above your stated 10-knot cruise speed. My guess is you need to get well above 4000 rpm to get on plane, and then throttle back to 3000 to 3500 rpm to remain on plane. Your other choice is to go slow at hull speed. When running between plane and hull speed you are just pushing a bow wave and wasting fuel.

[rsmith]

check the bottom for growth a couple barnacles on gas engines will kill it. Like rust barnacles never sleep!

[Bill Allen]

SOunds to me like the four barrels were wide open. Check and make sure it will turn rated rpm which I doubt. Either a horible fouled bottom or way wrong props. But if you were plowing (which you were) it will suck fuel. I had a 33 pacemaker with big blocks and had flow scans on it. It would keep getting better mileage (after you put it on plane) the farther you pushed the throttles foward, then the four barrels opened. I had to push them wide open, get the boat up on plane then pull back to cruise. Bill

[wmfels]

are you the one with the vacuum issue?

[Bayside Bert54]

Your fuel tanks might be on the small side for those 427's and the 36 Hatt might be on the large side ... The diesel engines are a better match for that boat and safer too although more expensive at purchase. (except these days when they seem to be giving all boats away!!)

The 427's are just fine for coastal cruising/fishing and are more economical in many ways than the diesels for 200 or so hours per year usage.

As a comparison ... my Bertram 28 has the 350 ci gasoline engines and 200 gal fuel tank ... total range is still not great ... 200 nm or so.

Mike

[Jaxfishgyd]

WOW.... just got back to the dock today after spending 5 days in Fernandina, a 47 mile trip each way.... Burned less than 60 gals ...

[Bill Allen]

I checked my fuel burn on the way from Brielle N.J. to Marathon Fl on one of the easier runs. Most of the time we had quite a bit of wind and seas. On a normal run I got 1.8 mpg (intracoastal) at an average speed of 8-9 mph. I could have done a bit better at 7. This is with 6-71n's (310hp). Temps stayed at 170-175. Bill

[wmfels]

as per your previous posts you're running the boat inefficiently its all or nothin. speed it up or slow it down