New Age Trawler/Motorsailer; Kite assisted PowerYacht

[sigurd]

hi apex, do you know the weight of the flying part of the skysail AP?

[apex1]

Originally Posted by sigurd

hi apex, do you know the weight of the flying part of the skysail AP?

No I do´nt remember! But it must have been far below 20kg in the early stages of development. At one of the first testruns I have seen one man handling it with ease. The present apparatus might be around 5 or 10 kg I guess.

Regards
Richard

[apex1]

Originally Posted by brian eiland

Do you have some sort of chip on your shoulder? It's as though any efforts beyond Skysail's are bogus.

Not bogus Brian! Not serious, or not as efficient, thats all.

I think Gino realizes the shipping industry is persuing the technologies...ie his quote, "The shipping industry is actually pushing the limit of kites a little faster than the recreational side, so we may see some of this development come out of the shipping industry because they have a lot of reasons to get some power out of the wind."

Does that mean he is aware of several commercial run applications? No, that means there MAY be something in the future. Typical US arrogance!

[sigurd]

5kg, that is similar to the weight of a 30sqm (ultralight) kite...

I guess the smallest kites for it must be huge?

God bless old Peacock.

[apex1]

Originally Posted by sigurd

5kg, that is similar to the weight of a 30sqm (ultralight) kite...

I guess the smallest kites for it must be huge?

God bless old Peacock.

That was the first fullsize kite, about 160m² with a lifting/pulling force of about 3 tonnes. Recent studies have shown that the pulling force is much higher than calculated. The recent kite that size pulls 4 -5 tonnes. Do´nt have the data at hand. So whats 5kg?

I assume you did ask for the control unit? Not for the whole kite???

[sigurd]

5kg? Not sure you'd notice it. But, you would, because the kite would crash! (yea thats what I asked for)

[apex1]

Originally Posted by sigurd

5kg? Not sure you'd notice it. But, you would, because the kite would crash! (yea thats what I asked for)

Sorry do´nt understand that.
What was your question, the control box or the whole flying stuff? Including rope and wire?
The blackbox is about 5kg as mentioned. The 160m² kite has a volume of about 2m³ and was handled by a crane (incl. the storage box though)! The whole shebang with hydr. mast, cable and rope drum, storage box etc. will have more than 1500kg, maybe 2 tonnes is my estimation from what I´ve seen.
The actual kite of that size pulls 8 tonnes btw!

[sigurd]

My wording was bad in the above attemted joke.

Yes, I asked for the flying control unit weight. Since these are motorsailers, and probably seldom are fighting to keep a kite aloft, 5kg is probably not a noticeable extra weight. And as you say the kite itself is a huge, heavy thing so 5kg will drown in the noise so to speak. Even if I scaled the blackbox weight to the kite areas I'm used to, it would hardly be a party killer.

Thanks for the info, I'm very interested.

The type of line used is also interesting. For 300-600kg strength kitelines, linear spectra with a very tight spectra sheath is generally thought to have very good strength, weight and low drag, owing to the roundness, and the higher frequency (probably also lower amplitude) flutter than looser braids get (I think - from experience). As ropes get thicker, maybe other considerations change this?

[apex1]

Spectra or Dyneema it was, I know, but do´nt ask me for any data. And they made a hughe drama about the whole connecting "rope" including the power and data cable.

[mikeharwood]

Hello ,

I have been following this thread with great interest. I have come across a
kite that looks quite interesting, and am wondering what the thoughts of
those with more relevant experience might be ? I have no affiliations with
omega sails.

Regards
Mike Harwood

www.omegasails.com

[apex1]

Looks like a possible solution in small scale, simple setup.

[brian eiland]

I believe one misunderstood concept with both 'pulling kites' and downwind sails is the fact that as your vessel starts to reach a reasonable speed in the same direction the apparent wind 'pushing' the kite or sail the force of that wind imparted to the kite or sail is greatly diminished. (if your vessel reaches 10kts in a 20kt wind, your kite only sees 10kts of wind, so your vessel will not likely see 10kts of speed, but MUCH less)

The para-kite form is a 'flyable' form, and utilizing this feature is important to make the best use of a 'downwind device'. Flying the kite allows one to double or triple the wind speed over the wing form of the kite or sail. Then remember that the pressure of the wind (on the kite) increases as the square of the velocity...much more power from a smaller kite.

[apex1]

Sure brian,
thats why I said "small" and "simple"

The aerodynamic wing kite has up to 8 times the power when flying figures (speed).

Regards
Richard

[Guillermo]

Looks neat and simple, indeed.
Although I don't believe a single person is able to deploy the kite (at the video, someone is taking care of keeping the boat going backwards while the guy at the bow deploys the kite), I think it can be of use for small motor boats, not only recreative but also commercial fishing ones. I specially like the apparent easyness to fly the kite again after dropping on sea surface, by simply going astern with engine.

Cheers.

[apex1]

Yes Guillermo, a waterstart is a good argument. But a "coming home" propulsion has no engine to go astern, when things go wrong. And of course two people to handle that system is one too much, no matter what they claim.