Quicksilver XS 380 HD problem

[superpuntar]

Hello,

I am new to this forum, i have been searching threads for the last two hours and did not find the answer to my problem;

I have a Quicksilver XS 380 HD with Yamaha 20 hp 4 stroke outboard. The boat suits my requirements except for one thing.
When i power up and it comes ot of the water it becomes unstable; it's hard to drive in a straight line without corrections. This happens on still water also.
It's abnormal motion is "cyclic": it leans a bit to the side, turns a little and then "jumps or leaps" into correct position. And then all over again and again... Needless to say, that the ride is quite unpleasant.
I tried diiferent trim posittions, different weight distribution, speed, and keel pressure. When i asked people for advice, someone mentioned air bubble forming under the boat.. maybe.

Has anyone had similar problems with an inflatable boat? What else could i try changing (maybe tab-trim over prop?)? Could that be constructional error?

Thanks for your answers!

And please excuse my bad english.

Bojan

[Poly]

Do you mean:

The boat comes onto the plane (most of the hull rises out of the water). Then one of the sponsons (tubes) leans over towards the water, and bounces causing the other side to touch and this process repeats itself.

If that is what you mean we call it "chine walking" and you should find some threads on here now you know what to look for.

[Locozodiac]

Hola Bojan...

Will need more info to reach a technical vredict

01-Is the 380 an air mat, aluminum or wooden floor, specify which ?

02-Are the side joinners (lateral aluminum bars which tights the floor to the boat) correcty positioned, that is the thickest part must face the fabric floor and have to be well even centered between floor boards.

03-Is the engine well transom centered ?

04-Hard to tell if all air chambers of your sib are correctly inflated, as I suppose you don't use a manometer to inflate to at least 3.0 PSI including the keel. ( a very important issue for correct performance many users don't pay attention to, other problem is where to find finding appropiate manometers)

05-Have you have been boating alone while experimenting balancing your weight. Is so the best position is to sit in the middle of the floor with your arm extended (in a confortable position) to reach the tiller. Though a 380 is a large sib to be used alone, will need counterweight buddies to perform better.

06-If your engine has a trim anode under the tail, see if it's turn to a side, probably out of adjustment causing the sib to lean/turn to one's side.

Here is some technical data, see if your sib is inside these boating parameters.


Happy Boating

[codprawn]

I have a Quicksilver 3.1 with a wood floor - I find it can be quite easy to get the air keel out of shape which alters the bottom of the boat - make sure when you inflate the keel it looks correct underneath!!!

It does sound like a classic example of chine walking.

This page provides loads of good general info.

http://sites.mercurymarine.com/porta..._schema=portal

[Channel Ribs]

Originally Posted by superpuntar

When i power up and it comes ot of the water it becomes unstable; it's hard to drive in a straight line without corrections.

As Codders has said, this sounds very much to me like the keel section is not in line. The advice about checking the engine set up is also sound, but the keel would be my first point to check.

Can you get a photo of the underside?

Let us know how you get on?

[superpuntar]

Hello,

done some reading on chine walking and It seems to me, that it describes my problem quite well. Except, since i got a small boat and not so much hp, the effects of chine walking are not so frightening as they could be..

First, answers to LocoZodiac:
1. The floor is ALU
2. Side joinners are correctly positioned (and done qiute easily compared to other boats such as HonWawe for example)
3. Centering engine is something, that i will be working on when trying to solve this problem (did it before)
4. I always use manometer and inflate to recommended pressure (i also always take into consideration temperature and pressure changes during the day.)
5. weight distribution experiment was the first thing i have tried changing - no real effect
6. Yes, trim anode under the tail is there

To malthouse: i will take pictures, as soon as i get to the sea and the water temperature reaches a few more degrees, my wetsuit is only 5 mm thick. When i think about that problem; can the keel really be out of place, when it is inflated and the boat is in the water? I mean, it shoud "jump" into correct position by itself. Could there be a difference if the keel is inflated on shore or when the boat is in the water?

SO, from all that i have read, i will try:

- changing engine position horizontaly (left - right)
- changing engine position vertically (lift it up al little bit)
- changing trim (allthough i have allready done it 100 times)
- changing the position of trim anode
- check the position of inflatable keel from under the boat

Do you suggest something else?

I hope that will be enough. I will report on "test results" (in about one month).
Thanks for all your help,

BOjan

[Locozodiac]

Before you do all the trial & error experiments described on your post, inflate your keel to 3.5 PSI or 0.25 Bar, the bow aluminum floor has a big hole, see if the keel is correctly positioned in the middle of the hole and not to one side, deflate a bit, correct and re inflate if required, raise your sib with both end cones touching ground and look under to see if the keel (will see a big ball) is well centred in the midle of the long striped bottom fabric. Check this at the beach before placing engine and prior launching to sea, re test performance...

If you move the trim tab, mark factory position before in case you need to reset to original setting.

Happy Boating

[jyasaki]

Originally Posted by superpuntar

Hello,
4. I always use manometer and inflate to recommended pressure (i also always take into consideration temperature and pressure changes during the day.)

Do you inflate while in the water, or on the trailer? If you're inflating to the recommended pressure on a warm or hot day on the trailer, then splashing the boat, you are probably running at less than recommended pressure in-water. Do a recheck after the boat has been in the water for ten or fifteen minutes.


jky

[Locozodiac]

If you inflate keel while on water you could have a mis aligned keel and not be aware of, it's better to check correct presure/keel aligment on shore and re check keel pressure once on water, re infate if required.

Happy Boating