Reply To: saildrive

Steve, I’d be very interested to know how those Torqueedo’s perform.

For batteries, it seems that the good old 6v Trojan T-105 golf cart batteries are hard to beat for value.
Li batteries are obviously much better weight per amp hour but very, very expensive and can be dangerous, core meltdown isn’t pretty at all. http://www.valence.com/SafetyVideo.asp There are some Li batteries that are not dangerous but are pricey. http://www.valence.com at about:
U24-12XP: $ 2,000 (<50 pcs.); $ 1,500 (50 - 250 pcs.); $ 1,200 (>250 pcs.)
Of course if you calculate the number of cycles etc. it works out about the same or less cost as the T-105 but there is a 4% annual loss so unless you are using it every day it doesn’t compete price wise but definitely gives you a weight advantage. I guess it all depends on how much motor time you need if you’re a coastal cruiser and how much spare cash you got lying around. These batteries would be great for a electric car that you use every day but I don’t think they qualify for a boat. If you plan on going cruising I would look at taking the minimal amount of batteries and using a generator.

I’ve been scratching my head with this electric option for quite some months; I’m now considering these options reasonably seriously:
Stiletto sail drive with a Lemco LEM-200 motor and a 4 quadrant controller for regen under sail. Apparently you can get about 10-15% regen under sail over 3 kts. So 10 hours of sailing over 3kts will give you an hour of motoring at the average speed. (This is a guess at the moment I’m working on getting reasonably accurate numbers for this)
Twin Torqeedo outboards, 4Kw total, their efficiency is very good but sill trying to figure out if they have enough power to get to 6 knots. (I need this much power cause the wind almost always comes straight down the southern California coast, so going north is at night mostly under power)
Either option with a 28V DC/4.2Kw Ecycle generator in the cockpit. (http://www.ecycle.com/APU.html) DC generators are apparently better due to losses in conversion from AC.

This all sounds great but power storage is still a big issue, so unless you have big $ to drop on many li batteries every few years you’ve got to think of a generator option for trips longer than 40 min or when you get into some sticky situation.

I’m leaning toward the Stiletto because I bought my boat with a 30hp outboard on the back and it’s no good at all. Cavitation is a big problem when there are swells, which is most of the time. Having the prop in the center sounds like a far better idea to me and the price/efficiency of the hydraulic option scares me!

A warning on r-e-power, I don’t know who’s math they are using but their HP claims of their motors do not seem realistic at all. I emailed them and they said the 3000 can push her at 8 knots! Sounds fantastic but this just doesn’t add up I’m afraid.