Twin Diesels versus single

[Skag]

Great thread. I've got to put my vote in for a single and the prop protection it inherently provides when on a trawler with a full keel. However, as many others have said:
1) It must get perfect maintenance
2) Have all critical spares on board
3) The captain must know the engine intimately and how to quickly repair it
4) Good clean fuel - with a means to circulate and clean the tanks

In addition to the basics above, I require and have for my peace of mind:
5) Dry-stacked exhaust and keel cooled. This removes the sea water and main heat exchanger completely at a cost of sacrificing some internal space. This also means zero salt water running through anything in the engine room.
6) Mechanical, proven reliable engine that is run at a fraction of it's rated HP. My current is a 3306 Caterpillar (run at only 1,100rpms...), prior was a 6BT cummins (no salt water aftercooler, run at 1,600 rpms).
7) Spares to the extreme: entire fuel injection pump, starter, injection lines, injectors, fittings, full engine gasket set, all belts (x2) hydraulic/fuel hoses and fittings (to make my own custom hoses on the fly), heat exchangers (engine and trans oil), turbo charger, replacement filters (6+ of each), engine water pump, belts, alternator(s), hydraulic pump, power steering pump, steering hydraulic rams, steering hydraulic solenoid valves, enough fluids to replace at least 2x. I'm sure I missed something. My boat is full of spares - at 105,000 lbs I don't care about the extra weight. Spares are wrapped in oil impregnated paper to prevent corrosion, wrapped in bubble wrap and logged in a spreadsheet identifying location stored. If I had to buy these again, I would find a used engine and pull all of the parts - I likely have $10K+ in spares. I had always carried a spare prop as well - until I saw the price to replace the current large four blade I have on my 50' trawler.
8) Engine fuel shutoff - must be either mechanical lever or an "energize to shut down" solenoid. It baffles me why most diesels use "energize to run" solenoids. I've converted every diesel boat to mechanical or "energize to shut down" after I almost hit the breakwall when my engine decided to shut down (Cummins 6BT) due to some corrosion on an electrical connection. Very risky to have "energize to run" system with salt water ......... only a matter of time.
9) I do all of my own maintenance to make sure I know the engine well. It also helps immensely with saving $$
10) Engine alarms and automatic shutdowns. All the basic gauges + alarms + automatic shutdowns. When out of the harbor and on autopilot, I arm a shutdown system that can be triggered by low oil pressure, low oil level, high coolant temp or low coolant level. In close quarters or in the harbor, with a flip of a switch the shutdown system is dis-armed.
11) Tools - enough to tackle any repair. Including a welder. All critical specialty service tools for the engine.

I don't like to worry....

 

[VanBrudenship]

Thread getting a bit old, but here it goes. I just got my first twin screw boat. The learning curve is easy. The manuverability especially with a bit of a breeze is just amazing. Put it where you want without banging off the docks. Yes, it will burn a bit more fuel but the control, IMO is worth it. Also, the currents in many places can be strong and if one goes out you are good but on a single you better be ready to drop anchor in those places. All that said, there are some high HP downeast boats with bow thruster that I'd probably consider when I move up.

 

[Mac2]

Great thread. I've got to put my vote in for a single and the prop protection it inherently provides when on a trawler with a full keel. However, as many others have said:
1) It must get perfect maintenance
2) Have all critical spares on board
3) The captain must know the engine intimately and how to quickly repair it
4) Good clean fuel - with a means to circulate and clean the tanks

In addition to the basics above, I require and have for my peace of mind:
5) Dry-stacked exhaust and keel cooled. This removes the sea water and main heat exchanger completely at a cost of sacrificing some internal space. This also means zero salt water running through anything in the engine room.
6) Mechanical, proven reliable engine that is run at a fraction of it's rated HP. My current is a 3306 Caterpillar (run at only 1,100rpms...), prior was a 6BT cummins (no salt water aftercooler, run at 1,600 rpms).
7) Spares to the extreme: entire fuel injection pump, starter, injection lines, injectors, fittings, full engine gasket set, all belts (x2) hydraulic/fuel hoses and fittings (to make my own custom hoses on the fly), heat exchangers (engine and trans oil), turbo charger, replacement filters (6+ of each), engine water pump, belts, alternator(s), hydraulic pump, power steering pump, steering hydraulic rams, steering hydraulic solenoid valves, enough fluids to replace at least 2x. I'm sure I missed something. My boat is full of spares - at 105,000 lbs I don't care about the extra weight. Spares are wrapped in oil impregnated paper to prevent corrosion, wrapped in bubble wrap and logged in a spreadsheet identifying location stored. If I had to buy these again, I would find a used engine and pull all of the parts - I likely have $10K+ in spares. I had always carried a spare prop as well - until I saw the price to replace the current large four blade I have on my 50' trawler.
8) Engine fuel shutoff - must be either mechanical lever or an "energize to shut down" solenoid. It baffles me why most diesels use "energize to run" solenoids. I've converted every diesel boat to mechanical or "energize to shut down" after I almost hit the breakwall when my engine decided to shut down (Cummins 6BT) due to some corrosion on an electrical connection. Very risky to have "energize to run" system with salt water ......... only a matter of time.
9) I do all of my own maintenance to make sure I know the engine well. It also helps immensely with saving $$
10) Engine alarms and automatic shutdowns. All the basic gauges + alarms + automatic shutdowns. When out of the harbor and on autopilot, I arm a shutdown system that can be triggered by low oil pressure, low oil level, high coolant temp or low coolant level. In close quarters or in the harbor, with a flip of a switch the shutdown system is dis-armed.
11) Tools - enough to tackle any repair. Including a welder. All critical specialty service tools for the engine.

I don't like to worry....
View attachment 159521View attachment 159522View attachment 159523

Sooooo….you do have two engines

 

[sneal4600]

Thread getting a bit old, but here it goes. I just got my first twin screw boat. The learning curve is easy. The manuverability especially with a bit of a breeze is just amazing. Put it where you want without banging off the docks. Yes, it will burn a bit more fuel but the control, IMO is worth it. Also, the currents in many places can be strong and if one goes out you are good but on a single you better be ready to drop anchor in those places. All that said, there are some high HP downeast boats with bow thruster that I'd probably consider when I move up.

I will be getting to know a twin set up on my DF44 next May. Hopefully it is as short of a learning curve as you describe.

 

[Skag]

Sooooo….you do have two engines

LOL. Guilty. Some assembly required. I suppose if I take it up to the Aleutian Islands I’d even get a cylinder head and piston kits. I could always limp into an anchorage and make myself at home for a week. lol. I’m an engine junkie. The only thing that would stop me from not coming back is a rod coming through the block - with a properly maintained 3306 is not really credible.