T-Pain Is On A Boat: Re: [Electric Boats] Electric Repower Next Winter?

Thursday, May 7, 2015

Re: [Electric Boats] Electric Repower Next Winter?

Scott,

What kind of boat are you looking at repowering??

Just to balance the opinions....

As you do your analysis, price out and see what it would cost to add an outboard motor bracket to mount a 15 or even 25hp gas outboard.

There are a LOT of really great things about electric boats. But in my analysis, it is NOT the best option if you are really trying to repower with a key goal of being "cheap".

Probably the most expensive block of the system is the battery bank(s). And you have to be honest with yourself here. AGM batteries might be an acceptable option, but then you have to consider that you really can't run them down below 75% - meaning you need a lot more AH capacity than a novice might ballpark.

Getting your old diesel to work (reliably) is almost certainly less expensive than a full electric installation.

If your diesel still has life, then you may well be able to get away with a 10HP outboard to push you back in as a backup. For a while, I tried using a "10HP" equivalent Torqeedo electric outboard on the Catalina 30 that I owned at the time. Using AGM batteries, I could easily push a Catalina 30 (you don't say which 28' boat you have, but it's probably a bit narrower and weighs a LOT less...?) around enough to get back into the marina. The limiting factor is that a 10hp outboard on a C-30 isn't enough to back into a strong wind. And this may be a general problem with an outboard on a large keeled sailboat - you seem to need a lot more HP going backward into a wind than you do going forward - or maybe it's a prop issue.... but I digress...)

A 20hp gas outboard is around $3000.

Now - back to electric.

As I said above, my experience has led to the conclusion that gas is a cheaper option than electric.

If you REALLY want to go electric - you're NOT going to do it as the CHEAPEST option - at least certainly not the cheapest option for money immediately out of pocket (I'm not considering "all the $$ I'll save not having to buy gas for the next 30 years"...).

I still tried electric, even though it didn't make financial sense in my case.

For that matter, I still built a wooden boat, even though there wasn't any really good reason to do that either.

These are things we do because we WANT TO.

John

From: "'Sdolan' sdolan@scannersllc.com [electricboats]" <electricboats@yahoogroups.com>
To: electricboats@yahoogroups.com
Sent: Thursday, May 7, 2015 1:08 PM
Subject: RE: [Electric Boats] Electric Repower Next Winter?

Hi Scott,

Welcome to thinking about Electric. 8o)

Get in touch with Sally at www.annapolishybridmarine.com

They are very knowledgeable on boats your size and can help with equipment as well as costs. Their close and have the stuff to do a good conversion. In the long run trying to figure out what is the best and safest way of doing this is often cheaper than doing it with cobbled parts.

Now if you're looking for some cost savings and decide this is the way to go keep me in mind, I have 12 Northstar AGM's from good to excellent shape I'm going to be selling in the fall when I go to LiFePo's. A few are already spoken for but at 210AH ea. You could get what you need cheap.

All,

I am a new member (sort of, I have been lurking around and reading). I am on the bubble whether to repower my 28' sailboat to electric this winter. I had a scare this spring with the old diesel and am tired of the poor old thing giving me an anxiety attack each time I turn the key not knowing if it will respond.

I am a bit of a "green soul" and mechanically I am more skilled at assembling electronics than changing oil. But I am also a bit on the cheap side and the old girl is still in service. But I am seriously tired of the oily smell from the bilge, the extra care when filling the tank, and ashamed when I see some sheen from the exhaust water (seldom, but still not a good thing). I am in the Chesapeake, and more specifically the Baltimore Harbor, so I am just adding to the problem of our murky bay.

I am more of a day sailor/weekender with a full-time job, and the boat is not comfortably ocean worthy, so I am not concerned with the cruising lifestyle issues. The typical docking distance under power is about 3/4 mile up a channel each way. But I wouldn't mind ensuring that I have a 10 mile range for emergency – or for motoring the 5 miles up into the Inner Harbor to listen to a band play. I have the typical 30 amp shore power and a 2 bank, 12V standard system aboard.

Boat specs are far below, but I would probably think that this chart is close for power consumption on a 5kW 48V system – which is adequate in my mind (we are sheltered from heavy seas and don't have much for tidal currents in the northern Chesapeake). This is from a post for Bob's 30' by Mike from Electric Yacht of Southern California:

Speed & PowerKts Amps Watts

2.5 10 4803.2 20 9604.0 40 19205.1 80 38405.8 120 57606.4 160 76806.9 190 9120

Being cheap, and less concerned with racing sailing performance, I would probably go with the heavy AGM option banking four 100AH-ish (maybe a second bank if needing the range). The Lithium option is tempting, but unless someone has an awesome source (and I could package cells, I think I am capable) that I have not found, the doubling of cost is just too much. Assuming the math on AH is as simple as dividing by Amps, cruising speed of under 4 kts should fulfill my range needs with one bank.

So you are probably thinking at this point, "What is this guy even posting about? He seems to be doing the research." So what I wanted was someone to agree that all this jived, let me know if anything needed more attention, and maybe point me in the right direction for parts. Is there a local dealer in the Chesapeake area or is it all online orders? Is there a particular kit that everyone raves about. There seems to be a lot of piecemealling going on (maybe for price purposes). I will probably need to change my prop anyway. It is an old clunker - literally, it clunks, and vibrates like a washing machine when it refuses to clunk. Is the prop regeneration effective or even worth it?

I talked to my marine service shop and they could do the install and have done a few – but they don't do the design nor order parts, just installs. I would probably take it to them to gut the engine and peripherals – maybe they can salvage for parts a nearly a zero dollar net bill?

If anyone has any advice to throw my way, I would certainly be interested. Is there something I haven't considered? I am especially interested in the secret sources you have on where to get the goods. I don't want to cheap out and get garbage, but don't want to pay for someone's yacht mortgage.

Thanks,Scott P.

Sabre 28-2 1980LOA: 28' 5"

LWL: 22' 10"Disp: 7,900 lbs.Max hull speed: ~7 kts

Current Powerplant:Original Volvo 13hp Diesel

Max speed: 4-5 ktsOffset shaft outputBob,
I made a speed power table for your boat with a conservative assumption for a 48v system.

2 blade folding prop (specs unknown) in front of the rudder

20 gal. fuel tank

__._,_.___

Posted by: oak <oak_box@yahoo.com>

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