weird turning.

[Jack h]

HI,
we have a 5m humber assault with a 60 4/
When going fast on the plane, about 2/3 throttle and upwards it feels like our rib really dosn't want to turn, most ribs ive driven tend to bank over a little bit and lean into the corner making turning easier on the driver as your pushed into the seat.
On our rib it dosn't bank over at all when you turn, it feels bit like a go cart compared to a motorbike, a motorbike leans in, the gocart just turns, which is a little disconcerting as when you turn hard it feels like your going to be thrown of your seat sideways. /
thanks

[jwalker]

Humbers do tend to ride flattish but try trimming up a bit and see whether it helps.

[Jack h]

forgot to say, is there a solution to this? ^^^^^

[BruceB]

Assaults do corner very flat in tight turns, they also tend to skip sideways in really tight high speed turns. Trimming up will just cause cavitation in these hulls.
Unfortunately this seems mainly to be down to the shallow V config so there is little to be done about it.
Trimming down before high speed turns will help cavitation but won't stop it completely.
This is one of the reasons why my next boat will be a deep V!

[Chris]

Just been down in Cornwall for a week with a freind who has just bought a Humber (I think its the 5 meter one) It has mariner 90 on the back and certainly felt very unstable at high speeds. There was no way you could even think of trimming up without the boat feeling like it wanted to spin around the prop. Every time he went over about 27 knots you really had to watch it as it would start pitching left to right (chine walking) and if you did not cut the throttle it could get quite dangerous.

You could see when running along side of him that even at 25 knots only the back 2 foot of the boat was actually in the water.

Chris

[jwalker]

Originally Posted by Chris1573

You could see when running along side of him that even at 25 knots only the back 2 foot of the boat was actually in the water.

Then he needs to learn how to adjust it and drive it.

[Biggles]

Sounds like he is learning. Just asking for other peoples experiences by the sound of it.

[jwalker]

Biggles, you've maybe got Jack h and Chris's friend mixed up.

[jwalker]

Originally Posted by BruceB

Trimming up will just cause cavitation in these hulls.

Then mount the motor a bit lower. Don't blame the boat.

[matt h]

same happened to mine, had a mariner 90 on a 5.3 ocean pro, and i could never trust it in a steep turn!! felt unweildy

[Chris]

Originally Posted by jwalker

Then he needs to learn how to adjust it and drive it.

So what adjustment would you suggest seeing as he had the engine trimmed in fully?

Chris

[Downhilldai]

Chris1573: Does your Viper run similarly, ie with most of the keel above the water when she's on the plane?

[wavelength]

had a mariner 90 on a 5.3 ocean pro,

Ocean pros-completely different animal to an assault! excellent hulls.
we have driven them all, all round the world-destroyers/ocean pros and assaults.
As for the assault- well its never gonna be brilliant (or even good)thats for sure, but stick plenty of weight up there in the bow/anchor compartment and keep the fuel tank in front of the consol-makes a lot of difference but still nothing like destroyers and ocean pros.

[Chris]

Downhilldai The viper has a much deeper V than the Humber so was not so noticeable however with the Humber it was like it was skipping over the waves and almost airborne most of the time. The difference between the two boats was very noticable the Viper being much more stable and suited to rougher water.

I think the 90 is too much for the Humber and suggested to my friend that a 60HP would probably be enough!



Chris

[Downhilldai]

I was alongside a Viper like yours last summer and I noticed that almost the entire length of the keel was out of the water when she was planing. This looked strange, but didn't seem to affect the way she handled rougher stuff. I put it down to the large planing pad at the rear of the hull.

[Mollers]

Originally Posted by Downhilldai

I was alongside a Viper like yours last summer and I noticed that almost the entire length of the keel was out of the water when she was planing. This looked strange, but didn't seem to affect the way she handled rougher stuff. I put it down to the large planing pad at the rear of the hull.

I hope that wasn't me,it sounds like she was over trimmed. I love the 'defend what you own' attitude that prevails on this site. Perhaps it's an attempt to protect residual values rather than admit to any flaws.Or, having little or no experience of any other boats/engines/bits of electronics and not knowing any differently. It sounds like those Humbers handle like a skip.

[alystra]

Originally Posted by matt h

same happened to mine, had a mariner 90 on a 5.3 ocean pro, and i could never trust it in a steep turn!! felt unweildy

Merc 90 on 5.3 Destroyer. Absolutely solid heeled right over and provided you trim in a bit, no cavitation. Chine walk? At 40 knots,(WOT) trimmed right out with wavelets on the beam, yes - sometimes. Otherwise, no.

The engine is the pretty much the top weight for the boat, I believe, but with the anchor and a small inflatable dinghy stowed forrard, she's 'chust sublime'.

I spent part of yesterday floating in and around the Gulf of Corryvreckan with two other RIBnetters. The 5.3 Assault with 60 Yam (I think) is very different from my Destroyer above the water, but when we left the Bay of Pigs (North end Jura) the ebb was at its height and it was 'choppy' , but the little yellow assault looked a picture as she just zoomed away. Must have hit as many concrete blocks as I did, but it didn't show. At displacement speed they were trimmed well down by the bow though, so I guess they got it right.

Humber's been in business a long time, so they must be getting it right, even though some models seem to be better than others at some things.

[DM]

Originally Posted by Mollers

I hope that wasn't me

Nah. It was probably me but I don't remember him running alongside. Most of the time he was eating rooster.

[BruceB]

Originally Posted by jwalker

Then mount the motor a bit lower. Don't blame the boat.

Ouch,talk about jumping in with both feet!
Anyway the long shaft motor on mine is as far down as it will go without cutting the transom almost down to the waterline, this may make keeping the boat dry somewhat difficult so I think I will put up with the cavitation!
All Humbers are not the same, I have driven both Attaques and Destroyers extensively with my dive clubs over the years, this problem is specific to the Assault as it is very shallow V.
It is actually supposed to plane on the last few feet, it is flat for this purpose and make for a fairly fast boat in calm conditions. The downside is less than perfect rough water handling and turning capabilities.
The skipping/flat turns are because the hull isn't into the water much and can't really be helped. The cavitation is probably in part caused by the tube extensions holding the stern up in turns and in my boat specifically by the forward mounted console and fuel tank making it fairly bow heavy. However there is not a huge bouyancy reserve at the bow in the Assault anyway so mine may not be any worse than any other. I normally put all the dive kit at the stern so I may not have this problem with the boat loaded but have never tried, I don't throw the boat about loaded with divers and kit!
The Assault runs with the tubes in the water so there is not much scope for leaning over in turns anyway.

[jwalker]

Originally Posted by Mollers

It sounds like those Humbers handle like a skip.

You driven a skip on the water?

BTW, nice to see you back Mollers.