Hi Bill,
I'm no expert, but my understanding is that you want to center the ballast fore and aft as you mentioned, but spread it out laterally. The idea is that increasing the roll inertia will give you a less snappy action, and a more comfortable ride. I'm not sure if that "rule" would apply to your particular hull, but it's something to think about. Good luck on your project!
Jim McMillan
--- In electricboats@yahoogroups.com, Bill Spires <spiresac@...> wrote:
>
> A general comment on battery placement. In any boat you always want the weight
> as low and centered both fore and aft and port and starboard as possible. The
> laws of physics are harsh. If you put the batteries aft under the cockpit it
> will increase the hobby-horsing of the boat and reduce the efficiency as well as
> make for a rougher ride. Weight in the stern can also lead to a huge increase
> in drag. The momentum of the batteries accelerating and stopping as they move
> up and down will cause an increase in drag. Look at your wake from under the
> stern. It he water is disturbed or "Chasing the boat" the energy to do that
> came from your boat. When I used to race my J-24 we always put the 3 hp engine
> below on the cabin sole. Yes that 30 lbs not hanging off the stern made a large
> difference. That's also why you won't see race sailboats with anchors hanging
> off the bow and chain stored in the forward lockers. That being said we want to
> wind up with a livable boat so some compromise between the convenience of
> hiding those suckers and the safety and performance of placing them amidships
> must be reached.
>
> Capt. Bill
> The Palmetto State
>
>
>
> ________________________________
> From: Bill Spires <spiresac@...>
> To: electricboats@yahoogroups.com
> Sent: Sun, October 31, 2010 10:07:32 PM
> Subject: Re: [Electric Boats] I am thinking about considering building an E-Boat
>
>
> Thanks for the feedback. I will try to get some pics and post some numbers. I
> like the Rainbow hull because of it's shape. I believe it will have very low
> drag at 4kts. I think the stability will be fine with the keel removed and the
> batteries in with no mast. I want to remove the keel because I want to be able
> to beach the boat. We have a lot of unpopulated small islands in the lake with
> beautiful small beaches. With the width of the boat and the fact that the
> center of mass will be low I think it will be fine but I will perform a
> stability test to make sure. Reference meta center for more information on the
> subject of stability. Wish me luck. The square riggers relied on internal
> ballast and form stability so maybe I can get it to work for me. I really
> appreciate your thoughts and constructive criticism as they make me consider
> things I didn't think to consider.
>
>
>
> ________________________________
> From: danbollinger <no_reply@yahoogroups.com>
> To: electricboats@yahoogroups.com
> Sent: Sun, October 31, 2010 10:58:08 AM
> Subject: Re: [Electric Boats] I am thinking about considering building an E-Boat
>
>
> Bill, A word of caution about using sailboats as motorboats. Most sailboats are
> designed to have poor initial stability, but very good ultimate stability when
> heeled over. Motor boats are the opposite.
>
> The 1120 pound ballast/keel is half of the boat's 2250 pound displacement , and
> is partially there to resist the forces of the wind on the sails and provide
> lift, they are there to stabilize the hull.
>
> Even if you move the ballast inside by using batteries, it might not be enough
> to make a safe boat. This may or may not be an issue, considering you are using
> this on protected waters.
>
> The Rainbow hull sketch does seem like an easily driven hull, and there seems
> to be room to slide batteries under the cockpit.
>
> > I am thinking about building an electric boat and that is why I joined the
> > group. I think I have found the perfect hull for me. An old Rainbow sailboat.
> >
> > It is currently a complete sailboat but I plan to convert it to an E-boat only
> >
> > with no mast or keel. I have a 36 volt golf cart motor but I think I will
> >start
> >
> > off with just a trolling motor. The lake I live on is approximately 7 mile s
>
> > wide and 20 miles long with about 600 miles of shoreline. I need about 10-12
> > miles of range at about 4 knots. I think a 2 battery setup with an electric
> > trolling motor will give me what I am looking for. I will carry a small
> > generator to run the blender and provide a supplemental charge. I will
> > re-charge the batteries from shore power after a cruise and I am planning to
> >put
> >
> > at least on solar panel on with a diode just to keep the batteries topped.
> >
> > Any thoughts o the above?
> >
> > I would like to instrument the boat so that I can know exactly how efficient it
> >
> > is. If I go for a little sunset cruise how can I tell how many kilowatts it
> > will take to recharge the batteries? A spreadsheet that we could just plugs
> > some numbers into would be nice,,, and a computer programmed to do all the
> > calculations while we are out cruising would also be nice. Tie in the GPS as
> >an
> >
> > auto pilot and I can concentrate on running the blender.
> >
> > Are we having fun yet?
> >
> > Capt. Bill
> > From the Palmetto State
> >
>
Hi Bill,
I'm no expert, but my understanding is that you want to center the ballast fore and aft as you mentioned, but spread it out laterally. The idea is that increasing the roll inertia will give you a less snappy action, and a more comfortable ride. I'm not sure if that "rule" would apply to your particular hull, but it's something to think about. Good luck on your project!
Jim McMillan
--- In electricboats@yahoogroups.com, Bill Spires <spiresac@...> wrote:
>
> A general comment on battery placement. In any boat you always want the weight
> as low and centered both fore and aft and port and starboard as possible. The
> laws of physics are harsh. If you put the batteries aft under the cockpit it
> will increase the hobby-horsing of the boat and reduce the efficiency as well as
> make for a rougher ride. Weight in the stern can also lead to a huge increase
> in drag. The momentum of the batteries accelerating and stopping as they move
> up and down will cause an increase in drag. Look at your wake from under the
> stern. It he water is disturbed or "Chasing the boat" the energy to do that
> came from your boat. When I used to race my J-24 we always put the 3 hp engine
> below on the cabin sole. Yes that 30 lbs not hanging off the stern made a large
> difference. That's also why you won't see race sailboats with anchors hanging
> off the bow and chain stored in the forward lockers. That being said we want to
> wind up with a livable boat so some compromise between the convenience of
> hiding those suckers and the safety and performance of placing them amidships
> must be reached.
>
> Capt. Bill
> The Palmetto State
>
>
>
> ________________________________
> From: Bill Spires <spiresac@...>
> To: electricboats@yahoogroups.com
> Sent: Sun, October 31, 2010 10:07:32 PM
> Subject: Re: [Electric Boats] I am thinking about considering building an E-Boat
>
>
> Thanks for the feedback. I will try to get some pics and post some numbers. I
> like the Rainbow hull because of it's shape. I believe it will have very low
> drag at 4kts. I think the stability will be fine with the keel removed and the
> batteries in with no mast. I want to remove the keel because I want to be able
> to beach the boat. We have a lot of unpopulated small islands in the lake with
> beautiful small beaches. With the width of the boat and the fact that the
> center of mass will be low I think it will be fine but I will perform a
> stability test to make sure. Reference meta center for more information on the
> subject of stability. Wish me luck. The square riggers relied on internal
> ballast and form stability so maybe I can get it to work for me. I really
> appreciate your thoughts and constructive criticism as they make me consider
> things I didn't think to consider.
>
>
>
> ________________________________
> From: danbollinger <no_reply@yahoogroups.com>
> To: electricboats@yahoogroups.com
> Sent: Sun, October 31, 2010 10:58:08 AM
> Subject: Re: [Electric Boats] I am thinking about considering building an E-Boat
>
>
> Bill, A word of caution about using sailboats as motorboats. Most sailboats are
> designed to have poor initial stability, but very good ultimate stability when
> heeled over. Motor boats are the opposite.
>
> The 1120 pound ballast/keel is half of the boat's 2250 pound displacement , and
> is partially there to resist the forces of the wind on the sails and provide
> lift, they are there to stabilize the hull.
>
> Even if you move the ballast inside by using batteries, it might not be enough
> to make a safe boat. This may or may not be an issue, considering you are using
> this on protected waters.
>
> The Rainbow hull sketch does seem like an easily driven hull, and there seems
> to be room to slide batteries under the cockpit.
>
> > I am thinking about building an electric boat and that is why I joined the
> > group. I think I have found the perfect hull for me. An old Rainbow sailboat.
> >
> > It is currently a complete sailboat but I plan to convert it to an E-boat only
> >
> > with no mast or keel. I have a 36 volt golf cart motor but I think I will
> >start
> >
> > off with just a trolling motor. The lake I live on is approximately 7 mile s
>
> > wide and 20 miles long with about 600 miles of shoreline. I need about 10-12
> > miles of range at about 4 knots. I think a 2 battery setup with an electric
> > trolling motor will give me what I am looking for. I will carry a small
> > generator to run the blender and provide a supplemental charge. I will
> > re-charge the batteries from shore power after a cruise and I am planning to
> >put
> >
> > at least on solar panel on with a diode just to keep the batteries topped.
> >
> > Any thoughts o the above?
> >
> > I would like to instrument the boat so that I can know exactly how efficient it
> >
> > is. If I go for a little sunset cruise how can I tell how many kilowatts it
> > will take to recharge the batteries? A spreadsheet that we could just plugs
> > some numbers into would be nice,,, and a computer programmed to do all the
> > calculations while we are out cruising would also be nice. Tie in the GPS as
> >an
> >
> > auto pilot and I can concentrate on running the blender.
> >
> > Are we having fun yet?
> >
> > Capt. Bill
> > From the Palmetto State
> >
>
I've been a fly on the wall for the past month or so, taking in all your wisdom/experience.
I see that much of the conversation is about sail boat conversions. My interest is to build out a 40 - 50 foot floating cabin on the Mississippi. I lean toward a three tube pontoon configuration and the possibility of grabbing some junked Honda, Ford, or Toyota hybrid set ups (possibly including CVT transmission) to move it about.
My question - anybody out there playing with this size effort?
Charlie
Bill, A word of caution about using sailboats as motorboats. Most sailboats are designed to have poor initial stability, but very good ultimate stability when heeled over. Motor boats are the opposite.
The 1120 pound ballast/keel is half of the boat's 2250 pound displacement , and is partially there to resist the forces of the wind on the sails and provide lift, they are there to stabilize the hull.
Even if you move the ballast inside by using batteries, it might not be enough to make a safe boat. This may or may not be an issue, considering you are using this on protected waters.
The Rainbow hull sketch does seem like an easily driven hull, and there seems to be room to slide batteries under the cockpit.
Bill, A word of caution about using sailboats as motorboats. Most sailboats are designed to have poor initial stability, but very good ultimate stability when heeled over. Motor boats are the opposite.
The 1120 pound ballast/keel is half of the boat's 2250 pound displacement , and is partially there to resist the forces of the wind on the sails and provide lift, they are there to stabilize the hull.
Even if you move the ballast inside by using batteries, it might not be enough to make a safe boat. This may or may not be an issue, considering you are using this on protected waters.
The Rainbow hull sketch does seem like an easily driven hull, and there seems to be room to slide batteries under the cockpit.
----- Original Message -----From: Steamboat WillieSent: Sunday, October 31, 2010 4:40 PMSubject: Re: [Electric Boats] I am thinking about considering building an E-Boat
It pushes it about 5 mph, about the same with 1 or two persons aboard. I think it would go faster, but I believe the motor is at max revs. Trolling motors are designed for thrust, not speed. If I could find an aluminum prop I'd try a bit more pitch.
I'm using the standard controller and I think I have a lot of power losses there.
Willie
--- On Sun, 10/31/10, Bill Spires <spiresac@yahoo.com> wrote:
From: Bill Spires <spiresac@yahoo.com>
Subject: Re: [Electric Boats] I am thinking about considering building an E-Boat
To: electricboats@yahoogroups.com
Date: Sunday, October 31, 2010, 10:37 AM
Thanks for the feed back. I am going to put a trolling motor on my Old Town canoe and use it as a test bed to try out my system.. How fast does the 40 push your canoe and would a larger motor push it faster or you reaching hull speed?
From: Steamboat Willie <stmbtwle@yahoo.com>
To: electricboats@yahoogroups.com
Sent: Sun, October 31, 2010 8:30:15 AM
Subject: Re: [Electric Boats] I am thinking about considering building an E-Boat
I think you have a good start. Sailboats are easily driven hulls and removing the rig and ballast keel will offset most or all of the weight of the batteries. I use a 2 x 6v battery system on a 18' canoe, it gets me 20+ mi with a MinnKota 40. I'm not familiar with a Rainbow, but you might want a 24v system as you can use a bigger trolling motor.
I'm guessing you'll have to create your own spreadsheet.
A "kill-a-watt" meter can be used to determine how much AC power it takes to recharge your batteries. Plug your battery charger into it and it'll give you total power watt-hrs used, and other stuff. About $25.
A battery monitor such as a Link or Trimetric will monitor your battery consumption for you.
Good Luck!!!
Willie
--- On Sun, 10/31/10, Bill Spires <spiresac@yahoo.com> wrote:
From: Bill Spires <spiresac@yahoo.com>
Subject: Re: [Electric Boats] I am thinking about considering building an E-Boat
To: electricboats@yahoogroups.com
Date: Sunday, October 31, 2010, 1:41 AM
I am thinking about building an electric boat and that is why I joined the group. I think I have found the perfect hull for me. An old Rainbow sailboat. It is currently a complete sailboat but I plan to convert it to an E-boat only with no mast or keel. I have a 36 volt golf cart motor but I think I will start off with just a trolling motor. The lake I live on is approximately 7 mile s wide and 20 miles long with about 600 miles of shoreline. I need about 10-12 miles of range at about 4 knots. I think a 2 battery setup with an electric trolling motor will give me what I am looking for. I will carry a small generator to run the blender and provide a supplemental charge. I will re-charge the batteries from shore power after a cruise and I am planning to put at least on solar panel on with a diode just to keep the batteries topped.Any thoughts o the above?I would like to instrument the boat so that I can know exactly how efficient it is. If I go for a little sunset cruise how can I tell how many kilowatts it will take to recharge the batteries? A spreadsheet that we could just plugs some numbers into would be nice,,, and a computer programmed to do all the calculations while we are out cruising would also be nice. Tie in the GPS as an auto pilot and I can concentrate on running the blender.Are we having fun yet?Capt. BillFrom the Palmetto State
hello...
first post and havent done any searching yet but thought id toss this project into the mix. ive got a 42'LOA, 32'LWL, 19,000 pound sloop. cut-away fore foot/full keel. barn door rudder with prop aperture. shes and old school cca design with beautiful (to my eye) lines, and a bare hull restoration. and since i dont have a diesel id like to incorporate and electric drive.
my requirements are as follows...
the boat will be a liveaboard cruiser. not interested in racing, and the bottom will always be impeccably clean (its a pet peeve).
i only need 75% of hull speed (@5 kts) for 2 hrs a day, basically in and out of the slip and down and back the fairway.
i can charge from a shore chord but will have some solar/wind/towed log charging when anchored out.
i like the idea of regen capability while underway.
i dont mind carrying a gas/propane genset for emergency/general charging or continuous running in flat calms.
im quite handy and can do all the work myself.
so...ive only got about 5,210 questions. among them...
can i cannibalize an electric golf cart and "marine-ize" as much as possible and fullfill the above requirements?
ive got deep bilges, do i put one big forklift battery down there or are many smaller ones a better idea?
i like lead/acid as they are cheap and available worldwide but how do they hold up to the sloshing around and outgassing in the bilge? and 24 or 48vdc?
roughly how large a battery bank for propulsion only would i need and how big a prop (3 blade i presume for the regen) and what size motor?
and if these questions are too basic for this forum just point me in the right direction and ill get out of your hair. thanks so much in advance for any help..
rob
