Hi all, is light weight is always good for FE ? with good balancing of course.

That used to be the general rule with all boats. I have found that with todays powerful brushless motors and lipo batts you can build them a bit heavier and not lose as much performance. In my opinion build it light if you are racing and heavier if you are just playing. I build mine a bit on the heavy side so that they wil survive some good blow overs.

It's all about hull design and set up. Some racers have reported that when racing a boat that was designed to run NIMH on LiPo cells, it did not hold down in the corners because it was too light. I don't know of any hulls that are designed to run LiPos at the moment. Maybe some of the Micro boats of course.

Is lighter always better? No. You get to a point where the thing just isn't going to stay on the water. If you had some method of dynamic ballasting, or moving weight to where it needs to be, then lighter becomes practical even at very light weights and big power. Sort of like the unstable aircraft that require constant computer management of control surfaces. Density of the medium and stability are the 'biggies'. Not to mention $$$.
- 'Doc

That all depends on what you mean by better ?
My Renegade Rigger weighs in at 13 oz. WITH the battery ready to run and will run circles around a SuperVee 27. Took a little tuning and you need nice water but she FLYS.......tons of FUN !

there's always going to be a point or points where you go too light and you have a poorly made plane. Which is why aerodynamics comes into play the faster and lighter you go. Also your hardware and it's ability to adjust to these changes comes into play. It's a balance of all these factors that decide how light your boat can be.

Example of a poorly designed light boat. My stupid billings jet boat. The boat is so wide that when loaded and in the water, the impeller isnt more than 10% in the water. This is bad, takes forever to prime, takes forever to recover from cavitating and cant get to WOT, because it turns into a skipping stone. The only way to fix the problem is to add a lot of weight. Which then leads to one more fix, dump the boat. Sometimes it's the only way. the example is a bit off topic, but shows even a "properly" setup boat can be too light right from the start.