T-Pain Is On A Boat: [Electric Boats] A Dilemma

And don't forget to sell the engine before you remove it. A really good engine
sitting on the dock is a boat anchor.

Personally, I would think hard before changing out a good working engine on a
sailboat. Learn to sail first. Most sailors end up putting very few hours on
their engines in a season. I would definately replace a problem ICE with
electric, but see little point in replacing a good running one in a sailboat.

Storm Connors

I just bought a Buchan '37 whose hull is perfect and whose inside is bare,
and whose engine has run for a total of 15 minutes. Its a Westerbeke Pilot
20, reputed to be able to put out 20 HP to the propellor. My calculations
from displacement and waterline length using Dave Gerr's book, Propellor
Handbook lead me to believe that the engine is undersized and that I need
24 HP or 18 KW.

I looked in on the Nonsuch conversion using the Thoosa 9000 at 9 KW and the
35 foot C&C using an electricyacht 180i at I think 8KW and see that their
owners are pleased. So, my dilemma is why are they happy when they have
only half the power required in their conversion. Is this a trick?

I'd rather go green, but its a big step to scrap a perfectly fine
installation of a diesel for a flyer on something that's more expensive.

Cheers,
Al Maxwell

Messages in this topic (5)
__________________________________________________________
1b. Re: a dilemma
Posted by: "Mike" biankablog@verizon.net mbianka2000
Date: Sat Apr 9, 2011 6:00 pm ((PDT))

Al:

I am happy for a number of reasons since I went electric but, in terms of your
engine question. I converted the Nonsuch 30 BTW. On my 30 foot 16,000 pound boat
I had a Westerbeke 27 which was a 27 HP diesel engine. It was fine for the boat
but, 5 knots was the top speed I could tolerate when it was running because of
the noise and vibration. It worked fine for ten years until one day it didn't.
You know the rest of the story. The thing about electric compared to diesel is
that the electric motor only has to turn the shaft and prop. The diesel has to
turn several hundred pounds of fluids, metal crank shafts, water pumps, oil pump
and an alternator so that by the time the power gets to the shaft about 2/3 has
already been used up so you are at the 9 HP level at least on my setup. So the
Thoosa 9000 works very well for me. I'll let others who are more knowledgeable
about all the mechanics chime in on the specific details but, I'm happy with my
system. I do
think your boat may be underpowered with the current engine but, because it is
pretty much unused you should be able to get a good price for it if your decide
to go electric and sell it.

--- On Sat, 4/9/11, almxwll@gmail.com <almxwll@gmail.com> wrote:

From: almxwll@gmail.com <almxwll@gmail.com>
Subject: [Electric Boats] a dilemma
To: electricboats@yahoogroups.com
Cc: alvan.m@shaw.ca
Date: Saturday, April 9, 2011, 9:06 PM

Hi,

I just bought a Buchan '37 whose hull is perfect and whose inside is bare, and
whose engine has run for a total of 15 minutes. Its a Westerbeke Pilot 20,
reputed to be able to put out 20 HP to the propellor. My calculations from
displacement and waterline length using Dave Gerr's book, Propellor Handbook
lead me to believe that the engine is undersized and that I need 24 HP or 18 KW.

I looked in on the Nonsuch conversion using the Thoosa 9000 at 9 KW and the 35
foot C&C using an electricyacht 180i at I think 8KW and see that their owners
are pleased. So, my dilemma is why are they happy when they have only half the
power required in their conversion. Is this a trick?

I'd rather go green, but its a big step to scrap a perfectly fine installation
of a diesel for a flyer on something that's more expensive.

Cheers,
Al Maxwell

Messages in this topic (5)
__________________________________________________________
1c. Re: a dilemma
Posted by: "Rob Johnson" dopeydriver@yahoo.com.au dopeydriver
Date: Sat Apr 9, 2011 6:09 pm ((PDT))

This is the engine http://www.westerbeke.com/productBrochures/w20.pdf .
It is made by Bukh , and is one very tough little diesel , a gem.Designed to be
used in lifeboats .
The stuff I have put up gives a good rundown on the diesel , now see if you can
find some performance figures for electric motors to compare it to.
If you decide to go electric , you will have no difficulty finding a buyer for
the Bukh.
Regards Rob J.

________________________________
From: "almxwll@gmail.com" <almxwll@gmail.com>
To: electricboats@yahoogroups.com
Cc: alvan.m@shaw.ca
Sent: Sun, 10 April, 2011 7:06:13 AM
Subject: [Electric Boats] a dilemma

Hi,

I just bought a Buchan '37 whose hull is perfect and whose inside is bare, and
whose engine has run for a total of 15 minutes. Its a Westerbeke Pilot 20,
reputed to be able to put out 20 HP to the propellor. My calculations from
displacement and waterline length using Dave Gerr's book, Propellor Handbook
lead me to believe that the engine is undersized and that I need 24 HP or 18 KW.

I looked in on the Nonsuch conversion using the Thoosa 9000 at 9 KW and the 35
foot C&C using an electricyacht 180i at I think 8KW and see that their owners
are pleased. So, my dilemma is why are they happy when they have only half the
power required in their conversion. Is this a trick?

I'd rather go green, but its a big step to scrap a perfectly fine installation
of a diesel for a flyer on something that's more expensive.

Cheers,
Al Maxwell

Messages in this topic (5)
__________________________________________________________
1d. Re: a dilemma
Posted by: "Sally Reuther" smreuther@gmail.com smreuther
Date: Sat Apr 9, 2011 8:24 pm ((PDT))

Al,

Capt. Mike is absolutely correct - by the time the diesel engine delivers
the energy to the shaft it has already used quite a bit of it. My husband is
an electrical engineer and he explains it that you can roughly figure kw x3
to see what size electric motor will replace a diesel on your boat. So, a
9000 (or 9kw engine) x 3 replaces roughly up to a 27 hp ICE. As Mike said,
the electric only has to run your propulsion so all of that energy is going
right to the prop. My husband, David, has read David Kerr's book several
times over and has it pretty well digested now. :-)

Go electric - you'll be happy with it!!!!

Sally

On Sat, Apr 9, 2011 at 8:15 PM, Rob Johnson <dopeydriver@yahoo.com.au>wrote:

>
>
> This is the engine http://www.westerbeke.com/productBrochures/w20.pdf .
> It is made by Bukh , and is one very tough little diesel , a gem.Designed
> to be used in lifeboats .
> The stuff I have put up gives a good rundown on the diesel , now see if you
> can find some performance figures for electric motors to compare it to.
> If you decide to go electric , you will have no difficulty finding a buyer
> for the Bukh.
> Regards Rob J.
>
> ------------------------------
> *From:* "almxwll@gmail.com" <almxwll@gmail.com>
> *To:* electricboats@yahoogroups.com
> *Cc:* alvan.m@shaw.ca
> *Sent:* Sun, 10 April, 2011 7:06:13 AM
>
> *Subject:* [Electric Boats] a dilemma
>
>
>
> Hi,
>
> I just bought a Buchan '37 whose hull is perfect and whose inside is bare,
> and whose engine has run for a total of 15 minutes. Its a Westerbeke Pilot
> 20, reputed to be able to put out 20 HP to the propellor. My calculations
> from displacement and waterline length using Dave Gerr's book, Propellor
> Handbook lead me to believe that the engine is undersized and that I need 24
> HP or 18 KW.
>
> I looked in on the Nonsuch conversion using the Thoosa 9000 at 9 KW and the
> 35 foot C&C using an electricyacht 180i at I think 8KW and see that their
> owners are pleased. So, my dilemma is why are they happy when they have only
> half the power required in their conversion. Is this a trick?
>
> I'd rather go green, but its a big step to scrap a perfectly fine
> installation of a diesel for a flyer on something that's more expensive.
>
> Cheers,
> Al Maxwell
>
>
>

Messages in this topic (5)
__________________________________________________________
1e. Re: a dilemma
Posted by: "Eric" ewdysar@yahoo.com ewdysar
Date: Sun Apr 10, 2011 12:42 am ((PDT))

So my first question is: you want to change the engine because you have noticed
that your boat is underpowered while motoring? With a brand new driveline,
you'll be taking a loss, regardless of what you want to switch to. If it works
really well, why would you tackle a conversion?

But if you're set on creating a project, there are two common conversion ratios
used when switching from ICE to electric. The first one is 1kW of electric for
every 3hp of ICE. On your boat, that would be about 6.5kW. The problem with
this conversion is that it assumes that the ICE was appropriately sized to begin
with. The second ratio is more consistent with 1kW for each tonne of
displacement. For your 13,000 pound boat, that works out to 6.5kW of electric
drive.

The biggest change in going to electric is letting go of the idea of motoring
around at hull speed. Even if your motor could do it, your batteries won't last
long. Most of us cruise at 1/2 to 3/4 of hull speed to get reasonable range
from our battery packs. As a very rough estimate, every time you slow down 1kt,
you double your range. So if your boat has a hull speed of 7kts, you'll be able
to go 4 times as far at 5kts. Once you accept that you don't need to drive
around at hull speed, you can pick a driveline that will support the speeds that
you'll actually use.

My 5 tonne Cheoy Lee Bermuda 30 ketch has a hull speed of 6.5kts. The old
Yanmar 12hp diesel maxed out around 5.5kts. My new 5.5kW electric drive from
Porpulsion Marine pushes the boat to 6kts.

I would suggest getting familiar with your new boat before you make major
modifications so that you can determine exactly what changes will best fit the
way that you actually use the boat.

Fair winds,
Eric
Marina del Rey, CA

--- In electricboats@yahoogroups.com, almxwll@... wrote:
>
> Hi,
>
> I just bought a Buchan '37 whose hull is perfect and whose inside is bare,
> and whose engine has run for a total of 15 minutes. Its a Westerbeke Pilot
> 20, reputed to be able to put out 20 HP to the propellor. My calculations
> from displacement and waterline length using Dave Gerr's book, Propellor
> Handbook lead me to believe that the engine is undersized and that I need
> 24 HP or 18 KW.
>
> I looked in on the Nonsuch conversion using the Thoosa 9000 at 9 KW and the
> 35 foot C&C using an electricyacht 180i at I think 8KW and see that their
> owners are pleased. So, my dilemma is why are they happy when they have
> only half the power required in their conversion. Is this a trick?
>
> I'd rather go green, but its a big step to scrap a perfectly fine
> installation of a diesel for a flyer on something that's more expensive.
>
> Cheers,
> Al Maxwell
>

Messages in this topic (5)

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