Avon unstable at speed - Page 4

Chris · 03 March 2013, 21:54

....the engine being too low combined with incorrect trim would all lead to the trait you described.

Nos4r2 · 03 March 2013, 21:57

Quote:

Originally Posted by Chris

....the engine being too low combined with incorrect trim would all lead to the trait you described.

Yup.

A Caribe (OP's prev rib) with the relatively shallow V hull would have been far more forgiving of being trimmed wrongly.

teamplonker · 04 March 2013, 22:05

It was such a nice day I thiought I would take the day off and get on with moving that console.
Thanks jock for glueing it down with grip fill as well as screwing it, that made it so much easier to get off

Nos4r2 · 04 March 2013, 22:11

Quote:

Originally Posted by teamplonker

It was such a nice day I thiought I would take the day off and get on with moving that console.
Thanks jock for glueing it down with grip fill as well as screwing it, that made it so much easier to get off

It's also the correct way to do it

Unless he's used the wrong product it's not Gripfill it's probably Sikaflex 291 or the equivalent..
You should use it when you replace it as well or you'll end up with a rotten deck as water gets down the screw holes

teamplonker · 04 March 2013, 22:30

Quote:

Originally Posted by Nos4r2

It's also the correct way to do it

Unless he's used the wrong product it's not Gripfill it's probably Sikaflex 291 or the equivalent..
You should use it when you replace it as well or you'll end up with a rotten deck as water gets down the screw holes

Will it matter as it has the flooding hull ?

Chris · 04 March 2013, 23:28

Quote:

Originally Posted by teamplonker

Will it matter as it has the flooding hull ?

Yes, the deck is made of ply and the water will ingress into the ply the screws will let go and your console will disappear over the side when you are turning.

willk · 04 March 2013, 23:29

Quote:

Originally Posted by teamplonker

Will it matter as it has the flooding hull ?

Not if you don't mind eventually standing in the flooded hull.

Rogue Wave · 05 March 2013, 06:36

Quote:

Originally Posted by teamplonker

Will it matter as it has the flooding hull ?

Are you Johnny Fuller?

If you are not then I genuinely do not believe your problem lies with your consoles position it certainly shouldn't affect yaw that much.

Your transom looks poor and without doubt your engine is in the wrong position and I agree with rib teccie that your very poorly blocked flooding hull outlet may not be waterproof so you may be enjoying some free surface effect.

Are you absolutely sure that your transom is dry and solid, because if its flexing that gives you all sorts of handling issues.

I am fairly sure your hull was a deluxe by the way. The last 5.4 we did was very well set up I will try and post some pics of the engine /transom.

I'm taking the 5.4 out soon if you want to come down to Southampton I'll take you out and show you what a well set up 5.4 drives like

http://www.rib.net/forum/attachment....7&d=1323282431

what a transom should look like before the engine goes on

http://www.rib.net/forum/attachment....1&d=1321123720 note the surplus holes are sealed and filled using epoxy putty

teamplonker · 05 March 2013, 07:21

The hull was dry when i opened up the seal, only condensation

The transom seems solid, I took all the sealent out last night and drying it out today then fill it up with fibre fill later.

Does anyone know what these wooden things are ?

teamplonker · 24 March 2013, 01:44

Console moved forward, extra one added, transom cleaned up and deck painted. Time to get on the water.

treerat · 24 March 2013, 09:01

Quote:

Originally Posted by teamplonker

Console moved forward, extra one added, transom cleaned up and deck painted. Time to get on the water.

Good luck

teamplonker · 28 March 2013, 21:37

As it was such a nice day here today and I had cut my holiday In snowy Brixham short

I decided to take the boat out into the docks for the first time since I repositioned the console, Unfortunetly I am really disappointed with its performance.
After about an hour of just running around slowly and getting used to the feel of it again It only managed a meager 32-33 mph.
After messing about with the trimming I found that it ran better trimmed in slightly to bring the front down, this made it feel more stable and no chine walking.
Should I expect to get more speed or is that it ?

Rogue Wave · 28 March 2013, 22:12

i think that a bit of a result with that emgine. I was out today with our 5.4 with a Yammi 90 ( lighter and more powerful engine ) and mine was maxing at 38 knots

Its looking good nowadays

A1an · 28 March 2013, 22:23

I would've thought a few more kn/mph would've been achievable. Saying that the Honda 75 is a large lump.

Our 5.4 with a Yamaha 75 tops out at 35kn/40mph

Ian_st · 28 March 2013, 22:33

30+ in the docks..... Lucky you did not get caught, or is there a speed free area.

teamplonker · 28 March 2013, 22:34

38 knots ! , if my quick calculation is right that's about 42 mph.
I was expecting that kind of speed from this set up, I guess i was way off.
Its probably a good thing it does'nt as i still feel a little jittery after the last time out with the chine walking.
I feel safer with my little caribe and she hits about 35 mph but much more stable.

Do you think if i were to swap the engine for the yamaha 90 it would feel more stable or just go faster ?

teamplonker · 28 March 2013, 22:40

Quote:

Originally Posted by Ian_st

30+ in the docks..... Lucky you did not get caught, or is there a speed free area.

I had a word with the Harbour masters first and asked nicely if i could test the boat in the basin.
Eat a little humble pie give a big smile and hope for the best, this usually works. Ive been testing my boats down there since the early 90's, if your sensible they don't mind.

teamplonker · 28 March 2013, 22:41

Quote:

Originally Posted by A1an

I would've thought a few more kn/mph would've been achievable. Saying that the Honda 75 is a large lump.

Our 5.4 with a Yamaha 75 tops out at 35kn/40mph

Is that a 2 or 4 stroke

A1an · 28 March 2013, 22:50

It's a two stroke but 75hp is 75hp whether its 2 stroke or four.

It's getting to that 75hp that differs between the two.

teamplonker · 28 March 2013, 22:58

Quote:

Originally Posted by A1an

It's a two stroke but 75hp is 75hp whether its 2 stroke or four.

It's getting to that 75hp that differs between the two.

I'm thinking the weight difference between the two is a big factor, Ive only ever had 2 strokes before and am aware that they are lighter.
I just went for a 4 stroke as i thought it would be more reliable and better on fuel.
I'm not sure it was the right decision now