Twin engines

[Island Fish Lifter]

Oh yea, I almost forgot. Charlie, I never said you were wrong, In fact I think youre very knowlegable, probably one of the smartest guys on here. I find it easier for me to simplify things. Therefore, I expect most other people, who arent mechanics, prefer simple answers. I dont even know what a coefficient is[]

Fill the dam tub!

 

[Charlie]

Dave, I don’t have to surf the net, for this one!

I agree in keeping things simple! What you don’t know about me is, I too have a little experience as a mechanic, along with many things, and I do NOT claim to be a good mechanic – I’ll leave that to you, as that is not or ever will be my profession. And might I add, a good one is very hard to find! However, I have been a pilot for quite a few years (1976). I also have preformed duties of Aviation Maintenance Officer and Test Pilot. I know this might sound a little unbelievable and a bit mind boggling to most, but the United States government has spent - "well over" a million dollars in educating and training me, so based on that... I should know what the “four forces” and “coefficient of drag” are, at least until my Alzheimer's Disease progresses, "without surfing the net".

As far, as not knowing what coefficient is - "Google" it, it will be there!

Thank you for the complement!

 

[Island Fish Lifter]

When I said "drag", I meant efficiency loss in general.

Fill the dam tub!

 

[Island Fish Lifter]

Im not a complete idiot.. some parts are missing![]

Fill the dam tub!

 

[Charlie]

I don't think there are no parts missing?

I assume you surfed and understand “coefficient of drag”… and you understand the meaning and how the forces will either work together or against each other? Now in a boat, when you throw in your “thrust” make sure you account for your “propellers” (two props are "usually" more efficient than one, but not always), as different props will = a different thrust equation… and when that is all combined, it will equal your efficiency. I know you are not a complete idiot, but not sure you understand? As after you throw all these equations together you can either spend a lot of time trying to figure them out yourself, or simply get out the “performance charts”? The charts are a lot easier! The charts posted are accurate for those particular engines! If you look at them, they will give you the correct answer to your question. If you have different engines… you will need to get their performance charts – as all are different!

As all these forces interact, they are "a little" more complex then suggested, that is why it is "way" easier to just get the charts out - they have been tested. If I have missed or misstated something, anyone please feel free to jump in and correct... as my chosen profession is also NOT an engineer, specializing in aerodynamics!

Then after all this, I have to ask.… if you understand all the forces involved and how they are relating to each other and looked at the charts, what - parts are you missing?

 

[Last Chance]

Wow Charlie, I just went cross-eyed...

Last Chance Fishing Adventures

www.lastchancefishingadventures.com
www.swiftsurebank.com

 

[Charlie]

Yea... it is kind of a scary number, isn't it?
They probably didn't get a very good return on the their investment... or monies worth!

 

[nedarb2]

quote:Originally posted by C.S.

I'm going with twins for the new boat,do you guys run seperate fuel filters,batteries for each motor?

Yes to fuel filters - for batteries you have 2 with a switch so you can decide if you want each battery to run only 1 motor, both motors, or electronics (i set mine to "all" so both engines are run on both batteries (and the electronics are off both batteries) and either engine running charges both batteries. I know lots of guys run 1 battery for the engines, and 1 battery for the electronics. Thats good for if 1 battery dies, your other one isnt tied in with it so you have a back up to start 1 engine, then flip the switch to charge the other battery and start it.

 

[nedarb2]

quote:Originally posted by C.S.

I'm going with twins for the new boat,do you guys run seperate fuel filters,batteries for each motor?

Yes to fuel filters - for batteries you have 2 with a switch so you can decide if you want each battery to run only 1 motor, both motors, or electronics (i set mine to "all" so both engines are run on both batteries (and the electronics are off both batteries) and either engine running charges both batteries. I know lots of guys run 1 battery for the engines, and 1 battery for the electronics. Thats good for if 1 battery dies, your other one isnt tied in with it so you have a back up to start 1 engine, then flip the switch to charge the other battery and start it.

 

[Charlie]

Redundancy is a good thing!

With twins you should have “at least” two batteries, each dedicated to each engine. One engine - charging one battery, if you have 2 engines charging one battery you do run the risk of “over charging” a battery and/or batteries, not a good thing and that can easily be done with twins! I have three batteries, one battery for the port engine, one for starboard. The third battery is tied to my starboard, which is the “bank” used for the house. The batteries feed to a “main” buss, which controls everything; including my downriggers and all electronics. I have a battery switch for both and can charge either and all batteries, so I can run that main buss from either engine if needed.

When I unplug from shore power and go fishing for a day, or so - I have never had any issues, but as much fishing I do offshore (without shore power) I all ready know I am going to run my house bank down. That is a fact, the only question is how fast and when, and that is based on what I am running. There have been a lot of times (with no shore power) and when trolling, I have switched to “both” to have both engines charging my #2 starboard bank, but you need to be careful doing that, not to overcharge the battery and/or batteries.

 

[Charlie]

Redundancy is a good thing!

With twins you should have “at least” two batteries, each dedicated to each engine. One engine - charging one battery, if you have 2 engines charging one battery you do run the risk of “over charging” a battery and/or batteries, not a good thing and that can easily be done with twins! I have three batteries, one battery for the port engine, one for starboard. The third battery is tied to my starboard, which is the “bank” used for the house. The batteries feed to a “main” buss, which controls everything; including my downriggers and all electronics. I have a battery switch for both and can charge either and all batteries, so I can run that main buss from either engine if needed.

When I unplug from shore power and go fishing for a day, or so - I have never had any issues, but as much fishing I do offshore (without shore power) I all ready know I am going to run my house bank down. That is a fact, the only question is how fast and when, and that is based on what I am running. There have been a lot of times (with no shore power) and when trolling, I have switched to “both” to have both engines charging my #2 starboard bank, but you need to be careful doing that, not to overcharge the battery and/or batteries.