Transom Failure

[Bigmuz7]

Originally Posted by codprawn

I seem to remember the Millenium Bridge and our local harbour defences were both designed by experts using CAD - I don't think Brunel had access to computers and yet I would far rather trust his engineering............

Excellent point Codders .. the man was a genius

[Cookee]

Originally Posted by nikster

cookee...... im not sure i know of any Rib mfr's who have a Hydronamics expert on their books with the Savitsky spreadsheeds for working out all loads and stresses... when you have this data and model then put in your gucci design in to the cad machine, it works it all out to ensure nothing breaks and gives you the smoothest / optimum ride.

Thats why Halmatic cant make ribs for 30k!!!! the MOD takes no chances and Avon, Halmatic etc have departments that do nothing else other than model new boats and designs and work out the stresses, flexing momentum, maximum KW rating and rig the boats to a HUMS system to datalink the stresses through its operating environment and better understand computational fluid dymnamics and hydronamics.

Making fast ribs is fun, but making them properly that last for tens of years and remain structually sound for their life is something that the Rib industy is not renowned for.....!

I've only been messing about in them for 30 years, but as the saying goes - you get what you pay for, some rib mfr's are great, others are ok, and some we laugh at - but each to their own...

I'm uncertain as to what you mean by "Gucci Design", but I assume it wasn't a compliment.

Our 770 (I presume that's the boat you're talking about) was derived from our race boat hull that was designed by the very well respected Lorne Campbell, and I'm sure he is aware of all of the calculations and other stuff that went into many boats that have failed over the years.

What I am trying to point out that designing a mould and therefore a hull on a computer doesn't count for anything when you're swimming about in the icy cold North Sea in November with only a set of tubes above the surface. The reliability of any boat is down to the guy who built it and interpreted the drawings correctly. For example Kevin (Kitten on here) has building boats since he was in shorts, both for himself and for others including, Marine Projects who make Princess and Moody boats, and I would trust his experience and accumulated knowledge above many. You only have to see the sort of stuff we get in here to repair where respected builders have fallen short of what was needed to keep a race boat together. I am not claiming we are perfect, but as we have broken stuff at the extreme with offshore racing experience I can safely say our building techniques really have been tested! Indeed it is the associated products such as lifters and saddles that break first. We also have our CE surveyor take a very critical look at our boats (I have no idea what calculations he uses - life is too short!), and he agrees that our boats are are "Fit for purpose".

Lugnut - As Nikster says only very few manufacturers are big enough to do the whole thing by CAD with dedicated departments, but as Codprawn says basic engineering (and pre computer days) can still produce a product that is "fit for purpose", and designing a boat with the latest CAD technology doesn't guarantee a good product that any more than without.

[codprawn]

Cookee and I agreeing - what's the World coming to???

[Cookee]

Originally Posted by codprawn

Cookee and I agreeing - what's the World coming to???

No need to be concerned I don't intend on making a habit out of it!

[Poly]

Originally Posted by nikster

im not sure i know of any Rib mfr's who have a Hydronamics expert ...

Thats why Halmatic cant make ribs for 30k!!!! the MOD takes no chances and Avon, Halmatic etc have departments that do nothing else other than model new boats and designs and work out the stresses, .... ..and better understand computational fluid dymnamics and hydronamics.

ehh? is that not a contradiction then?

and I am quite sure halmatic could make boats for 30k if they wanted (they have already ammortised and recovered the development costs from the MOD and commercial contracts). They just don't want to. Its not where they have positioned themselves and they don't need the hassle for the relatively low returns in selling lower cost higher volume product.

[Lugnut]

Originally Posted by Cookee

Lugnut - As Nikster says only very few manufacturers are big enough to do the whole thing by CAD with dedicated departments, but as Codprawn says basic engineering (and pre computer days) can still produce a product that is "fit for purpose", and designing a boat with the latest CAD technology doesn't guarantee a good product that any more than without.

Whoa there, I am *NOT* one of the unwashed masses that blindly blieves CAD and CNC are the answer to everything. As I said before. Just another tool. You can drop a decimal point just as easily in a CAD application as you can with a pencil.

If you have a crummy engineer designing a widget it doesn't matter WHAT tools he uses, the result will be a crap product. On the other hand, if you have a competent engineer, why would you force him to use antiquated tools?

You certainly do not have to be a large company to use CAD technology. I regularly farm out jobs to a small machine shop. Some of those jobs were LITERALLY handed to them scribbled on paper grocery bags! They turned the ideas into working products, performed an FEA and thermal analysis, and turned out a prototype within two weeks. We finalized the design, passed both FAA and military flight certifications, and are now flying that widget in about 20 aircraft with more installations each month.

A competent engineer in my field commands a nice salary. I'd be a fool not to buy a 10K software package that would cut his labor costs and increase his productivity by a factor of **50** over hand calculations and hand drawings!

But first and foremost, you have to have competent engineers.

[codprawn]

What sort of widget and what aircraft - another passion of mine!!!

[Bigmuz7]

Before going off topic, part of the point I'd like to remind peeps about is this :

Northcraft has stuck a label on their boat saying its rated to 300HP. < Edited at the request of Northcraft - JK >. The boat clearly cannot withstand that kind of load.

The argument that the Verado is heavy is not valid either, as 2 x150 optimaxes is even heavier than the single 275 Verado.

The CE marking is a waste of time as has been proved, so who is going to stop manufacturers claiming their hull is capable of performance when it clearly is not ? and slapping any old sticker on the transom to rate it for HP

Have I been conned ? < Edited at the request of Northcraft - JK >

And ofcourse the good old customer pays ,.. and takes the loss on the chin .. again ..

[Lugnut]

Originally Posted by Bigmuz7

The boat clearly cannot withstand that kind of load.

The argument that the Verado is heavy is not valid either, as 2 x150 optimaxes is even heavier than the single 275 Verado.

The CE marking is a waste of time as has been proved, so who is going to stop manufacturers claiming their hull is capable of performance when it clearly is not ?

Have I been conned ? < Edited at the request of Northcraft - JK >

And ofcourse the good old customer pays ,.. and takes the loss on the chin .. again ..

My apologies, I certainly hadn't intended to hijack your thread with a discussion of CAD.

[Cookee]

Originally Posted by Bigmuz7

Before going off topic, part of the point I'd like to remind peeps about is this :

Northcraft has stuck a label on their boat saying its rated to 300HP. < Edited at the request of Northcraft - JK >. The boat clearly cannot withstand that kind of load.

The argument that the Verado is heavy is not valid either, as 2 x150 optimaxes is even heavier than the single 275 Verado.

The CE marking is a waste of time as has been proved, so who is going to stop manufacturers claiming their hull is capable of performance when it clearly is not ? and slapping any old sticker on the transom to rate it for HP

Have I been conned ? < Edited at the request of Northcraft - JK >

And ofcourse the good old customer pays ,.. and takes the loss on the chin .. again ..

The CE marking think is of use in instances such as this though - you can take the whole lot to trading standards and they should act on it. The fact that it was rated to that horsepower gives them some ammunition to use against the manufacturer.

Lugnut - I think we are in agreement then!

[nikster]

cookkee

I am not familiar with your product and would never slag anyones off - not my style.... im sure your boats are lovely but the topic was transom's delaminating with a heavy donk but within kw rating........ it happens and so does sh$t.....!!! lol

[Lugnut]

Originally Posted by Cookee

Lugnut - I think we are in agreement then!

I believe we are! lol!


Bigmuz7, has Northcraft been any more obliging or are you going to have to have repairs done out of your pocket someplace else?

[yorfuoj]

I agree with Cookie statements ... it is not enough to get a CAD designed boat, when the keypoint is the guy who stratifies the hull !

I had to repair a transom with the same kind of broken knee as Bigmuz had, there should have been 6 layers of roving glassfiber carefully handlaid - not easy to do into the knee negative and narrow mould shape - but there were only 2, and badly glued with bubbles - in otherwords, the main strength was the surface gelcoat ...
This work was probably made at the end of a week, when the guy was late to his appointment with a nice girl ...

CAD design ... ok, fine, but not enough

[Bigmuz7]

Originally Posted by Lugnut

I believe we are! lol!


Bigmuz7, has Northcraft been any more obliging or are you going to have to have repairs done out of your pocket someplace else?

Thankfully my dealer, who fitted the hull out, repaired it ,.. and I appreciated their support.. but it took a few strong words before they stepped in.. and they were woefully slow in doing it, which ultimately made me want to dispose of the boat.

Northcraft attempted a repair which was an utter joke .. I would strongly caution anyone to trust them to repair a .. (THEIR OWN) boat.. which is a shame as they do make some good hulls.. My dealer was FYM in Grangemouth, my thanks to Keith & Ivan for handling this difficult situation and I can gladly say I'm out of it now..

[IBWET]

I'm more interested in the Gem your hanging on too

(not stirring,just want a laugh)

[Bigmuz7]

Originally Posted by IBWET

I'm more interested in the Gem your hanging on too

(not stirring,just want a laugh)

Its no big deal, but, for a boat manufacturer they should be ashamed of themselves, ..as yet, I am at a loss as to why they didnt want to improve their product in the long run.. as I understand it, the 8.5 was an Osprey hull design, which I already said was a good basic hull, but it lacked a good degree of finesse and the tubes..... were debateable


In 10 years of RIBs and all Northcrafts .. I couldn't go to the damn thing without having to pump up the tubes every time I went out

Has me in mind to post a thread about that actually.. how often your tubes deflate

This Northcraft was a weekly occurrence for atleast one of the chambers every time and thats over three different boats that I've had from them.. they were all just as bad

[Downhilldai]

Your profile shows that you use a Valiant. What do you think of that?

[Bigmuz7]

Originally Posted by Downhilldai

Your profile shows that you use a Valiant What do you think of that?

Very good actually.. small & very good design thoughts have gone into this boat, how one compartment, like an anchor locker drains into the next, it has a fuel tank built in that has a filler with an overflow catch, that means it wont spill and contaminate other sectors of the boat should you over fill, and its easy to use the filler under the bow hatch, which has a breather so reduces your chances of overfilling. It has tube safety pressure relief valves, a generous tube diameter to start with, fair lead etc, dual grab robes inward and outward along the tubes and I must say, on the water I've been surprised at how well it takes rough water. Its not as deep V as some of my previous boats, but I havnt experienced a thump and bang ride yet

Ontop of that... I took a large force 6 breaking wave over the side a couple of weeks ago whilst fishing in the sea at a rough point, and I didnt feel threatened at all in this boat, despite taking a lot of water.. funny how you seem at one in some boats but not in others

edit .. I havnt put air in the tubes since the day I got it either ,.. general manufacturing quality of this boat is a mile away from what i've been used to .. I could go on

[Downhilldai]

Originally Posted by Bigmuz7

.. one compartment, like an anchor locker drains into the next, ...

Does the anchor locker drain into the void between the hull and deck?

[Bigmuz7]

Originally Posted by Downhilldai

Does the anchor locker drain into the void between the hull and deck?

Yes but unlike many other boats Ive had, there is no leakage through the deck from rain from this locker or any other components.. The bow locker where the anchors are, drains to the mid section, which drains aft, and they are designed to do this, so its not as if water will get trapped anywhere in the hull, and I'm not talking about a lot of water here compared to what I've been used to.

Crucially .. the lid for the bow locker is designed .. very simply.. with a u shaped profile round its edges, so no rainwater can penetrate its opening, so simple, yet forgotten by a lot of manufacturers.

In 2 weeks of on and off rain .. I think I got 1 pint of under deck water altogether half of which I think was condensation