Baker wrote:Wowie....this is the humdinger of all topics and you will get opinions all over the map. I am in the single engine camp.
Hummmm Lets see now???* To enjoy a single screw or a double screw... shall we let our minds wander!* Oh my, but I digress lmao... oooo*
On to more serious stuff about power boating... Most Joking Aside!*
At or below hull speed, if you run both engines in a twin screw simultaneously you get dual wear and tear, higher (not necessarily double) fuel cost, and twice the maintenance costs compared to running a single screw.* If you cruise the same boat at or just below hull speed with one twin running at a time, you cut the wear and tear in half, greatly reduce fuel costs (to the proximity of a single screw) and maintenance costs are cut not quite in half... pretty darn similar to the overall economy and power train costs of boat with a single screw... but... you always have the capabilities of twin screw for docking, fast runs if needed or desired, ability to better deal with certain rough sea conditions; and of course, a virtual guarantee that you always have get-to-port power capabilities (so long as you dont run completely out of fuel DUH!).*
We all know that engines as well as their entire drive line should be exercised on a regular basis.* Therefore, in a twin screw it is the alternating of engine use that keeps their usage hours in sync and power train mechanics in working order.*
Some cautions (and/or precautions) regarding alternating twin engine use schedules (other items not mentioned should also be considered):*
- To power along using one engine, without having the off engines shaft locked in position (so the off engines prop does not freewheel and turn the transmission without its fluids fully lubricating all parts), then the twin engines use schedule should be alternated each hour so the freewheeling transmission does not damage its interior and trany fluids are kept well dispersed inside both transmissions.
- If you use one engine for over an hour then it is wise to lock the off engines shaft in position so its prop does not freewheel and therefore no damage can occur to the off engines trany.* A locking method can be as simple as a vice grip on the off engines shaft.* Or, if you plan to often run one engine on and one off for long periods then you can get creative for developing a shaft locking mechanism.* Accesses to lock the shafts are individualized per boats engine area layout.
- Always check with trany manufacturer to make sure that one hour +/- freewheeling at hull speed will not damage your model trany.
- To not put too much stress on the running engine of a twin screw, i.e. be careful to not try and go too fast... at or below hull speed is the most comfortable for all mechanical items concerned... also to attain the lest gph!
- When alternating engine use; if done by the hour the off engine will still have residual heat from recent use, but, do let the newly started engine warm up for a few minutes before placing into gear and shutting down the other motor.* If alternating engine use after long periods then allow the engine being brought back on with full opportunity to warm up before engaging.*
The benefits of utilizing a single or twin screw power configuration are really not too far apart.* Personally, I enjoy a boat with creature comforts of two staterooms with a large salon, a big fly bridge, plenty of deck space, good sized swim step, a SD or plaining hull and twin screw... that can cruise at hull speed, or below, or above and, that by alternating engine use can be made to cruise economically too!!*
For long range fuel economy I believe a FD hull*with conservative diesel power (that is cruised just below hull speed) will provide the most economical overall experience.* But, if utilized wisely, twin screw in any hull design can also provide good economy and can always enable other operational options that a single screw simply cant achieve.*
With that said... I feel it is up to the perception, desire, and understanding of the boat purchaser, hopefully acting as the captain too, regarding what power source, size/style craft, hull configuration, make, accessories,*and interior accommodations are chosen.* When an informed boat Captain is also the purchaser, then the union of owner to craft can become electrically charged!* And yes, a love affair between the two can ensue!* There was a recent thread in this forum asking Do boats having feelings; well in my opinion sort of! - LOL ***
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