>Yes, I am still looking for stiff, fast(long&narrow), lightweight, easy to assemble boat with good payload and quality. ...Now I am considering two boats: Fujita PE-480EX - closest to my wishes but its stiffness is questionable
Ladoga-1 - cheap enough for DIY improvements
Read articles about Fujita - it has some waterproofing problems, leaks through and around the hatches. Seems like it can be easily remedied, - so this isn't a big problem. Sounds like it is more flexible than Feathercraft K1, and - not sure, just my guess - closer to Folbot Cooper than to K1 in flexibility.
If you are not very tall, you may consider Feathercraft Kahuna. It is easier to assemble than K1 (25-30 minutes), lightweight (16 kg stripped boat, without rudder or backpack), payload is 135 kg, and quality is very
>Changed rudder looks very similar to folbots and probably work like rudder from folbot. It is far from Kleppers or Feathercrafts rudder.
If it is a yoke foot control system like in Foldbots - it is not very comfortable. I tried it, and Klepper pedal system is much better. Also, I don't know what are the stern attachment details on "new" L1. Thin axle and yoke (at the stern) made of very soft metal, plastic fittings, ropes instead of cables, rubber brackets with narrow holes and a lot of friction, and brass sleeves falling out of these holes - all this makes old L1 rudder difficult to control and unreliable. Rudder lifting cleat near cockpit was just a mockery, poor illiterate attempt - I can't describe this. Considering that good clam cleat of that size costs only $4 in marine stores - I can't understand such a "design concept". I have no idea what was changed in the new rudder, and wouldn't like to bet my money again on something uncertain. You will need your rudder, paddling around Croatia and Greece coast - Greece can be very windy in summer. Buying directly in Russia, you won't be able to check everything in the store, and will have to bring it back to Russia within 1-year warranty term, if anything is wrong.
>I see Ladoga as DIY alternative to Tom Yost's DIY kayaks. Its low price could justify some work on boat IF basic design is good.
Basic design? Stiff frame = difficult assembling. Keelstrips is a good idea, but they are way too narrow (and you can't change this). Plastic fittings are designed poorly, they need a lot of care in assembling. Yes, you may use the skin and frame tubes, and redesign most of plastic fittings (= make your own) and replace all the hardware and hinges with a qood quality stainless parts, and make some changes to spraydeck, and replace spray-skirt. My mechanical skills were not enough to do all this on L1, and it didn't look like a good candidate for a sea kayaking even after all the possible DIY changes.
>K1 must be very good boat but paying 5(8!) times more for a quite heavy boat that is hard to assemble (at least time consuming) is just not good alternative for me.
Like you said, K1 and L1 are not in the same league, speaking of quality; their prices should not be compared. K1 could be remotely
compared to Folbot Cooper or Fujita 480, and in this league the price and quality difference would be much less. Also, consider that both Cooper and Fujita have lower payload than K1. L1 is same wide as K1, but 15 cm shorter, and has same or slightly less payload as K1.
Speaking of weight and assembling: post-2001 K1 weighs 24 kg without rudder and backpack; my L1 was also 24 kg without rudder and backpack. K1 takes 50 minutes to assemble, and L1 takes 50 on most days or 40 on good days, or 60 on bad days (its assembling and dissembling is very unpredictable, and always needs a lot of physical efforts - more than in K1). K1 is not the best boat for daytrips with assembling every time. L1 would be worse than K1 in that sense. If assembling that takes more than 30 minutes and a lot of efforts, you will not want to use it for just 6-7 hours day-trip without overnight stay.
Kahuna is, I think, the limit of what can be used for a day-trip, with 30 minutes assembling and 15 minutes dissembling. It is also the limit for a 65-70 kg paddler on 7-8 days trip with full supply of food and fresh water.
>In my opinion Klepper offers the best price/performance ratio (at least in Europe). Kleppers are robust and quality made BUT they are heavy and slow. Folboats are even slower except for Cooper witch has too much flex and too low payload.
Folbot Kodiak should not be any slower than Klepper AE1. I think, AE1 weighs slightly more and packs more bulky than Kodiak - but in Europe I would be tempted to get an old AE1 rather than Kodiak.
>I know that boats with aluminum frame are not best choice for sea paddling
Featehrcrafts and Folbots are aluminum; Klepper Alu-Lite is aluminum. When aluminum grade is good (not the case with Ladoga), and tubes are thick enough (Ladoga's tubes have very thick walls), and if it is anodized (not the case with Ladoga), and if the boat is waterproof enough (most boats are), then aluminum works fine in sea water - for many years.
>Money is not that big issue, price/performance ratio is.
Try getting a used K1 for $US 1800-2000 (preferably, post-2001). Pre-2001 models have heavier Hypalon skin (but they are much cheaper). Or a used Kahuna for $US1500 (they are all post-2001 - some with hatches, and some without).
>I have found some positive reviews for newer Ladoga on German forum.
Still want to take a chance?
... I can only wish you good luck. Probably, it can be used by people who live near water (preferably, not sea water), in their own homes, and keep Ladoga assembled all the time (or, at least, all the summer). Then, after some DIY work, it could be a reasonably good and cheap boat for river and big lakes paddling.