Getting rid of perfectly good diesel. Am I crazy?

I am in the early stages of a big project to build a liveaboard from a 34' enclosed lifeboat.
It is currently powered by a 70hp Sabb diesel with 80 hours on it, and maintenance done by the US Navy. It runs like a top, despite being 30 years old, and is pleasantly simple.

Now the boat. I have already started some fairly big changes to the structure of the boat, and the plans are to build a pilothouse right at the stern. The diesel takes up quite a bit of space in the last 8 feet of the boat, and while there are some interior layouts that would work with the diesel in place, I can't help but think that we would love to have the main cabin in the stern, and place a cockpit above. That's not really possible with the Sabb in place.

I would like to be able to travel up the inside passage with the boat, but wonder about adding a single or dual high thrust motor to the boat. To make this idea a bit crazier, I am in the negotiation phase of purchasing a donor boat, which has lots of great electronics, victron inverters etc, windlass, dinghy etc etc. Anyhow, this donor boat also has a 10kw brushless motor and controller running off over 10kwh of 48v batteries.

What if I install the 10kw motor in place of the Sabb. Sell the Sabb. Use that money to buy the High Thrust outboard, and live happily ever after with a "hybrid" boat, and the extra space.
I know nothing is ever as simple as it seems, but I think there might be a certain logic to this, especially as the donor boat purchase makes sense for me, even without the electric inboard.

Thanks in advance for any input. I do have access to lots of welding/machining equipment, and some of the skills to use them

 

Yes. You are crazy. Don't sell the diesel. Add the other stuff if you like, but keep the diesel.

 

I'd work twice as hard on the layout to save the diesel. A table or benches can be made from the doghouse.

 

That Sabb will most likely outlive you and any 10 "High Thrust" motors.
The power from a 10kw motor? About like a small garden tractor.
Where you want to cruise is quite often beset with strong currents, you need power.
What's that line from a John Wayne movie, something like;
"Life is hard, it's even harder when you're ,,,,,,".

 

I worked in a shop where one of the engineers had that saying on the wall some 30 years ago with a picture of John Wayne.

Hello Andre,
Great Lakes fish tugs (like my avatar) often had a helm station that was 2-3 'steps' higher than the main sole in the boat so the pilot could see over the cabin top. Maybe that idea could be ported to the lifeboat refit.

Fish Tugs Of The Greatest Lake https://www.harveyhadland.com/pics000.htm

 

While an engine is a pain to design around look at it from a broader design perspective. 50 gallons of diesel and that engine get you x amount of miles range, how much space would batteries plus outboards require for equivalent range.

 

At typical energy density about #6000 of batteries. Design around that, if that's easier than 50 gallons of diesel. That's around $200000 worth of batteries. Two year's pay for me to replace as much diesel as I can buy with a good day's pay. Sounds crazy to me.

 

@AndreLP , I'm in North Van when I'm not off Port McNeil. @BlueBell is in Victoria.

 

The generator and batteries will take more space than the current diesel and fuel tank.

 

If you want a generator, put one on the diesel.

 

@AndreLP have you seen these older threads on this Forum about lifeboat conversions?
If not, there might be some useful info in these threads in relation to your conversion.

Lifeboat Conversion to a Houseboat during COVID https://www.boatdesign.net/threads/lifeboat-conversion-to-a-houseboat-during-covid.65166/

What could be done with an enclosed lifeboat? https://www.boatdesign.net/threads/what-could-be-done-with-an-enclosed-lifeboat.63238/

 

Wow, Thanks for all the responses, looks like I need to set up notifications!
I realize that most people here think the diesel removal is a bad idea, and for the first year of ownership I've felt the same. Maybe it is, but as the space is going to be a living space 95% of the time, gaining 25% of the interior space felt like it was worth the trade. If you are looking at this as a homeowner, where a boat is for recreation, I would share your opinion. Certainly if I were looking for the best performance, I wouldn't have bought a lifeboat!
I'd be curious if anyone has experience with running a pair of high thrust OBs on a heavier boat. I know it's quite common on older catamarans, but it's hard to find much information about their effectiveness/economy.

Thanks to those who responded.

"I don't have much time for John Wayne, or those stuck in his era. "
-Me

 

Your boat, do what you want, don't think most of us here didn't warn you.
John Wayne, his era?
Yeah, that was back before effete dandies with pencil mustaches and thin leather shoes became pseudo
naval architects for popular boats from Europe, and decided that Nokia interiors and "panoramic windows"
were more important than seakeeping ability.

 

Are you hoping to use this for comparison with your lifeboat, and her 70 hp Sabb?
If so, you will find that the Sabb will win hands down, every time, on pretty much any comparison.

Taking this to the extreme (but you did mention a heavier boat....), how much power do you think the heavy boat in the photo below has?



She has a pair of 250 hp Caterpillar 3208T diesel engines.
Not a lot of power really for a vessel this size (she is 30 metres / 100' long, and 9 metres / 30' wide) - but these engines have 5:1 reduction gearboxes, and they are driving propellers that are 4' in diameter.

Now imagine putting a pair of 250 hp high thrust outboard engines on her (I know that they don't exist in this size, but lets imagine that they do).
How effective would they be?
I think they would act as egg beaters, and not provide much propulsive power.
But they are the same power as the inboard Cats......

 

Outboard power is not an option for all hulls, I’ve seen some very poorly engineered matches.
Bajansailors “eggbeater”analogy is quite appropriate!
Outboard motors typically use gasoline, and likely a lot more of it than the diesel.
A reliable solar electric cruising boat needs lots of sunshine, something that the OPs locale is not noted for!
Lacking charging capabilities, the diesel will need to remain anyway to power generator.
Some pictures would be helpful here, maybe there are some possibilities that are yet unexplored?
The Saab is not tremendously large or heavy, maybe by use of V drive or extended shaft it could be moved forward or back to better utilize interior space?