Swi-Tec Hydro-generator

About two years ago we installed a hydro-generator from Swi-Tec.

It is rated 600 watt, Price with bracket ca 3650 Euro, but it will probably set you back close to 4300 Euro with freight, cables and extra propeller before you can start to use it.


The bracket for mounting is very solid in Stainless Steel, they have other versions of brackets for different types of transom.


Relatively easy to mount, even though it is a rather heavy piece of equipment

It folds up rather easy, you firmly pull a thin rope, some force needed to release it, then you pull a tackle to fold it up, gloves is recommended for soft hands



The folding mechanism itself weigh 9,5 kg a rather heavy piece to store aboard, the lover part can be dismantled from the folding mechanism for easier storage, but still very bulky and heavy to handle. But when in place it is relatively easy to deploy and to fold it up from the water when not in use. After a while you get the feeling for how to do it.

When storing one need to take of the propeller else it will require a lot of space for storage, you also risk bending a propeller blade

The propeller is adjustable to suite your boats speed potential, the blades are made of aluminium, They are relatively brittle, we lost one blade by catching some Sargasso weed and a thin plastic bag, I thought that was not to expect so I contacted Swi-Tec and wanted a new propeller from them or at least a new blade. They answered nothing wrong with their propeller I have had “bad luck” actually they said the propeller is very solid and that they support their customers very well, well we do not agree to that!

Swi-Tec weed

They sent me this picture to demonstrate the strength of the propeller

The Electrical plug supplied we found not up to standard, so we used a normal 16 A European plug for shore connection

16 A Plug

If you klick on the short video-clip you can see it in action


So is this a good thing ho have?

I think not, it has some limitations

  1. The most obvious one and you might think I’m stupid even mention it. But it only works when you are sailing, yes of course you say. We have been blue water sailing for about 4,5 years and most of the time we are at anchor, we move about 15% of the time. We have Solar power which I and many other claim is the number one option,  if we sail  2-3 days we manage on solar power, the only need for the hydro-generator is when crossing for several days, which I think most cruisers do not do very frequent. But when crossing an ocean is it not a good thing to have? Well by having a smart regulator on your alternator you easily complement the solar during night by maybe running your main engine 1-2 h a day (we usually run our genset 2×45 minutes during night/morning), that will give you about 100 Ah 24v a day, to add to your solar input. If you make 30 days of ocean crossing in a year, I guess you are above average and that will add 60 h to your yearly engine usage. I do not know for how long one has a hydro-generator but maybe 10 years, that correspond to maximum 600 h of engine use for extra charging. The cost for the Hydro Generator is 4300 Euro divided by 600h gives 7 Euro Per hour engine use, and that is for a heavy user. But if you do not want to use fossil fuel then it might be a good complement.
  2. Sargasso weed if you cruise in areas with Sargasso weed you will be feed up with constantly cleaning the propeller. The Caribbean and the surrounding areas maybe as fare out as 500 Nm you will find plenty of Sargasso weed
  3. Output, the highest we have seen is 10 A 27V i.e 270 w doing 9 kn, not close to the nominal 600 watt. The reason for that is the regulator monitoring the state of the battery so if battery is 80-90% full, it gives maximum around 10 A even if you consume 10A using autopilot and radar.
  4. You do not want it on the stern when not in use. You need to take of the propeller, most probably also dismantle the folding mechanism from the rest of the generator else very heavy and difficult to store, find space down below where it is relatively easy to have access to it else you might not bother to bring it back up for a few days of sailing. Mainly use it for longer passages which one might make 1 or 2 per year.

Due to broken propeller on the passage between Hampton, Virginia to Antigua (+1600 nM) , plenty of Sargasso weed and that it fell apart just one day out from Bermuda on our way to the Azores we have not used it very much.


Just lucky I saw that it was falling apart else we could have lost it, when reaching the Azores I sent it back to Swi-Tec for repair, got it delivered back to La Coruna, so no use on that 900nM passage.

I would not buy a hydro generator again, not from any brand, the cost benefit is not good enough.

If you want one despite what I’m writing look at another brand, The Watt & Sea are popular but set you back another 1000 Euro, and have the same issue with monitoring the battery status and not including your consumption.