I can only go by my experience (36 Sport Sedan, 440 Chryslers). At planing speed, about 1 gallon (total of both engines) per nautical mile. At about 1 knot below hull speed, about 3.5 to 4 total gpnm. On mine hull speed is around 8 knots, and I cruise very efficiently at around 7 kts or so. At that speed, I'm just off idle - about 1,300 rpm.
A rough rule of thumb is to take the square root of the length at the water line and multiply by 1.34 to determine hull speed. Your 34's hull speed should be about 7.8 knots; a 7 knot cruise will be pretty economical. At a 9-knot cruise, you will be digging a big hole and using a lot of gas; yet it's not fast enough to be planing. There's a lot of information on the Internet about this; do a Google search for "hull speed." Other variables will be, single or twin engines (sounds like you have twins), and what condition they're in. Also, it will depend on how clean the hull bottom is -- for a 1,900 mile cruise it'd be worth it to have the boat hauled and the bottom pressure-washed in the sling - shouldn't cost more than a hundred bucks or so if you make arrangements with a yard to schedule it at a slow time when they need some work to fill time, and it shouldn't take more than an hour or so. If your carburetors haven't been overhauled for a while, find a good carb shop, pull them off, take them in to be rebuilt. Do this a comfortable amount of time before your planned departure so you can make adjustments after reinstalling. A really good shop will send someone out to go with you for a test run; though you'll probably have to pay for their time. But if you're going to burn possibly as much as 1,000 gal of gas at $3 a gallon, a couple of hundred bucks to be sure your chokes are tuned right will pay off. Make sure your chokes open completely when warmed up - if you have manifold-heated choke stoves, you might pull off the intake manifold and have the exhaust crossover cleaned out. Some engines are notorious for getting carbon blockages in the crossover. I once had a Lincoln with a 460, and the crossover was solid carbon - no heat to the choke stove; and 440 Chryslers are notorious for this. Ask me how I know. When this happens, you get one of two results: You either adjust the chokes to open completely but they won't close, leading to hard starting (my situation), or they're adjusted for easy starting but never open completely, leading to rotten gas mileage and shortened engine life due to being over-rich. Electric chokes won't have this problem, but carry a spare electric choke stove, because they'll fail sooner or later. I've had that happen, too. Goes without saying - have a complete tune-up done: new plugs and plug wires, cap and rotor. Points and condensers, too, if you have conventional ignition; and carry spares. Set the dwell and timing to spec. If you're not going to be doing any high-speed running, and your specs give a range of idle timing, aim for the more-advanced end of the range (if it says set to 5-10 degrees advance at idle, aim for 10). If you do this, however, pay careful attention to your engine sounds; if you get any "pinging" or spark knock, retard the idle timing. If you're going to be really thorough, pull the distributors out, take them to a shop with a distributor machine, and have the advance curve checked against spec. Distributor springs stretch over time and you lose full advance; or the advance weights will rust on their pivots and you won't have any advance at all. A rough check of your distributor advance mechanism can be made by pulling off the distributor cap, grasping the rotor, and twisting it back and forth. It should move through about 20 degrees or so against spring pressure, and return to the original position when you release the twisting pressure. If it doesn't move, suspect a frozen advance mechanism. This static test doesn't tell you anything about the condition of the springs, which is why I suggest having the advance curve checked on a distributor machine. Good luck - sounds like a fun trip. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "UnifliteWorld" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/UnifliteWorld?hl=en -~----------~----~----~----~------~----~------~--~---
