Plane Talking.....

[neilda]

I have all of ten hours clocked up - so there are many mysteries yet to reveal themselves.

One of them would be understanding the feel for being 'on the plane'.

Is it a case of trying to get and keep the boat level (horizontal) when travelling at speed? Or should the bow be slightly raised? How do you know you're actually on the plane - I am experimenting but am not confident I know what I should be feeling/seeing.

All tips gratefully received!

Thanks........

[bedajim]

Originally Posted by neilda

I have all of ten hours clocked up - so there are many mysteries yet to reveal themselves.

One of them would be understanding the feel for being 'on the plane'.

Is it a case of trying to get and keep the boat level (horizontal) when travelling at speed? Or should the bow be slightly raised? How do you know you're actually on the plane - I am experimenting but am not confident I know what I should be feeling/seeing.

All tips gratefully received!

Thanks........

That'll be that Ribeye for you

Did you do the PB 2 or are you learning as you go ?

[Chris]

Neil,

It depends on the set up however most ribs plane between 9 & 11 knots. In a lot of cases the bow will rise slightly as you power off then drop back down as the hull comes onto the plane.

The main thing you need to get the feel for is the trim whilst planing.... as you trim out the steering lightens and the hull starts to feel "looser" on the water, this is because by trimming out the engine you are lifting the front of the boat out of the water until just the rear of the boat is all that is left in the water. This is the most efficient way to run and you will also find the speed increases.

In a following sea it is always wise to be trimmed out as otherwise you risk stuffing the rib into the back of the wave in front as you come down into the troughs.

If you trim the engine back in you will feel the steering start to stiffen up a bit and you will see the bow drop back into the water. This is what you will be looking to do when you want to cut through rougher water and especially a head sea as you will want to keep the bow down as you go over the waves

It's basically a balancing act and judging of the conditions ahead of you so that the boat is in the right trim as you head into the various sea states you will encounter.

[Chris]

... Oh and dont be suprised if you get it wrong and end up with half a ton of water washing around your deck, I think everyone on hear at one point or another will have stuffed (3 weeks ago at Portland Bill was my last one as Matt H's better half will confirm)

[JSP]

Good advice of Chris (even if he did get Matt's wife wet lol)

After you've climbed over the hump start to trim out and as the hull frees it's self your revs will increase.
Good fun init?

[neilda]

Thanks Chris - I think I actually meant trimming.... my terminology is not fully nautical yet!

So ideally you'll run with the bow in quite a high attitude?

Do most boaters run with a lot of trim, only reducing or removing the trim for pootling about? When would you use negative trim? (If there is indeed such a thing?)

There doesn't seem to be much of an explanation in the Yamaha literature about trim - but I assume the midway point on the dial is a neutral (level) trim....

Thanks - sorry for dumbo questions!

[Steve_B]

"So ideally you'll run with the bow in quite a high attitude?"

No not really. Whilst it will depend on the boat and engine, the average RIB will be running quite level on the plane. As you transit from displacement to planning, you climb over your own bow wave and during this you may find that your bow lifts.
However, once over this, your bow will drop again and your now planning = speed increases rapidly with no more application of additional power.
At this point input babs of trim and listen and feel for increases in rpm/speed, note the trim angle. Keep doing this until either the RIB begins to feel unstable or the prop begins to cavitate, at which point trim the engine back in to the last angle it felt right. You will now have a better feel for what is right for your setup.
Do all this at lowish speed (3000rpm ish) so that if anything happens that you do not like, you still have control.

As said before though, I would strongly recommend doing at least the PWB level 2, with your own RIB, you will learn so much.
Regards
Steve

[Chris]

Neil,

Trim is all about feeling the boat. Each boat is different for example my current Osprey is very well balanced so when trimmed out is not running too nose high the whole boat is effectively out of the water yet still running fairly flat even when it is trimmed out. The down side is that it is slightly easier to stuff this one compared to my last Osprey which had more weight in the back.

However if the Rib is a bit heavy in the arse area it will tend to run a bit nose high when trimmed out which is ok if you are in a following sea but not very comfortable as you head into choppy conditions and can make for quite a dangerous situation if you are in rough head sea conditions as the rib is more inclined to pitch up as you head over the waves.

BTW all of the above is from my own fairly limited experience and there are a lot of other factors that may have an impact on the ribs performance and stability.

Weight distribution plays a big part and a full tank of fuel or 4 adults on board can really affect the performance of the boat and how you trim it.

[jyasaki]

Originally Posted by Chris

Neil,
In a lot of cases the bow will rise slightly as you power off then drop back down as the hull comes onto the plane.

The other thing to look at is the height your feet are over the water surface. Your feet will probably rise by a foot or more as the boat climbs out of the hole. Though admittedly, it can be tough to tell as your speed increases.

jky

[neilda]

Useful stuff - many thanks....

I have done a day with an instructor, we covered how to trim but I'm afraid a combination of excitement and too much information.... luckily I have remembered the more essential stuff.

[Hightower]

Something else you might like to consider is trimming in during tight turns as your prop might be trimmed too far out and will lose grip in the corners and start to ventilate.....Second thoughts perhaps this is better left till after you have mastered the straight line stuff

But worth experimenting with anyway

[BogMonster]

As somebody self-taught with no formal qualifications (no such thing around here - I had 1 go in the boat with the previous owner before I bought it so was completely green from day 1) - I know just what you mean about uncertainty and wondering if you are doing the right thing or not.

I think the advice to go for a PB2 is probably a good idea if you can - I've probably got some bad habits but I'm not sure what they are...

In my case I just mucked around with trim and speed until I figured out the best combination, without really knowing what I was doing at first, and a combination of observation of what the boat did, reading stuff on here and talking to other people involved with boats led me to figure out what worked best. I suppose I was fortunate in that there wasn't a lot to run into around here but it also meant there wasn't really anybody to learn from so I made a lot of it up as I went along. Best advice is to take it fairly steady with the throttle until you get the feel of the boat and under what conditions it can start to become unstable - mine is pretty good except with light fuel load at absolute WOT and trimmed out till it hurts, but the first time it did a chine walk wobble at 40kts I crapped myself however as with many things you learn by experience.

Taking off over a wave into a strong headwind and not being sure whether it was going to keep going up or land back in the water was another one of those "learning experiences" that defined the edge of the envelope, as was almost finding out the hard way how quickly a swell can rear up and break as it comes into shallow water, and getting most of the hull out of the water at less than 10 knots going over it.

Trim and its effect on comfort versus speed is something you will learn through experience, in my case it was a while before I discovered how much difference it makes heading into a choppy head sea having spent quite a long time battering my knackers flat on the fuel tank when the wind got up.

I guess the best advice is take it easy, experiment and learn from little mistakes rather than diving in head first and making a big one, now with a couple of hundred hours under my belt I feel quite happy in the way it performs but admit to having scared myself a few times - another fairly sound piece of advice is to generally try and scare yourself in a new way for the first time when you have nobody else in the boat!

[chewy]

The basics are trimmed in if you want the best performance from a standing start then trim out as you increase speed.
When heading into the weather/waves keep it trimmed in/bow down so you don't take off as much.
Running with the weather trimmed out so you don't stuff the bow.

Phill

[neilda]

Originally Posted by BogMonster

........ the first time it did a chine walk wobble at 40kts I crapped myself however as with many things you learn by experience.

................another fairly sound piece of advice is to generally try and scare yourself in a new way for the first time when you have nobody else in the boat!

I think I did the first part already - but not the second!

Just seen your address - you're a long way away.

Thanks Phill, useful summary.

I have some experimenting to do but feel I have understood the principal - developing the 'feel' is something I need to be hands on to do now.

[GJ0KYZ]

Originally Posted by BogMonster
"........ the first time it did a chine walk wobble at 40kts I crapped myself.."

I agree. Chine walking is effing scary at high speeds; you feel the boat's about to tumble out of control. It's caused by too much trim when going over an uneven sea. When you're trying out various trim levels be aware of this phenomenon and if it starts to happen reduce speed immediately. That way, the boat will settle back into the water and the wobbling will stop.


Have a look at my Flickr page: http://www.flickr.com/photos/gj0kyz/

[neilda]

I think I have done a moment of 'Chine Walking' - fully trimmed at 45 whilst experimenting. I instinctively slowed down, it felt like something akin to a speed wobble on a motorbike, very unstable.

If continuing to chine walk, do you end up swapping ends or stuffing? All of which sound hideous at speed.

[BogMonster]

Originally Posted by neilda

I think I have done a moment of 'Chine Walking' - fully trimmed at 45 whilst experimenting. I instinctively slowed down, it felt like something akin to a speed wobble on a motorbike, very unstable.

If continuing to chine walk, do you end up swapping ends or stuffing? All of which sound hideous at speed.

That's it. I can't answer the second part as to what happens next as I didn't give it time! It's happened a few times since but doesn't happen in any normal trim/speed range with my 115hp only when trying to get that extra 0.1kt top speed.

I imagine it might be a different story if you fitted the boat's maximum rated 150hp and the laundry bill would probably go up - anybody tried 150hp on a Destroyer 5.8?

GJ, try as I might I couldn't see any evidence of chine walk on those funny paper animals?

[Stoo]

Achieving the state of "On Plane" is a bit like reaching orgasm. It's hard to describe exactly, but you'll know when you get there...

[neilda]

Originally Posted by Stoo

Achieving the state of "On Plane" is a bit like reaching orgasm. It's hard to describe exactly, but you'll know when you get there...

So quite hard work, often not getting there and feeling dissatisfied afterwards?

Got it.

[chewy]

Originally Posted by neilda

So quite hard work, often not getting there and feeling dissatisfied afterwards?

Got it.

Your doing something wrong if your feeling dissatisfied after words...