Design faults.

[MikeJohns]

This metal boat was apparently built by a professional yard to a well known designers plans.

There appears to be an oversight here in the stiffening in one of the higher slamming load areas that should not have occured.

The photo is looking fwd. What assumption has apparently been made that would be incorrect ? (5 marks)

[jehardiman]

There is no chine stringer. The assumption being that the chine is self-supporting.

PS. I'd also have a look at the calculations at the fwd frame to floor; frame to deckbeam joint; and maybe panel shear. Cant really tell yea or nay from the photo.

[raw]

Hard to say exactly from a photo, but it appears the designer has assumed that the chine is giving support in the foremost frame spacings when the change of angle between the bottom and side plates does not allow for it. As such, there are now oversized panels up forward and the adjacent frame was probably calculated using a span that is less than actual.

(what he said)


Did you make a mistake mike?

[lazeyjack]

that boat would not pass a plan approval, I can see the floors seperating from the plates in short order It is this sort of thing which gets alloy a bad name, nothing is a strong as a properly built alloy boat, and nothing is as weak as a poorly made one , but in many countries, places, you must get accreditation BEFORE you start playing with real moneybuilt one
I found that girdars and deep ones to are the only thing that will hold a fast powerboat together
I had to give 5 years warrenty to my boats, and I have to say that boat would frighten me to death A chine stringer is not necessary,
I am sorry if this seems harsh critism, but some poor owner will pay for this
I find there are too many people calling themselves (designers architects) with absolutely no qualifications whatsover, I also find there are many handymen and small engineering shops who start up in our business, to make a living building boats I am not against learning, but accreditation first,
You can see by my right arm the depth of the girdar

[MikeJohns]

Yes

Where the chine runs out (angle greater than around 150 deg) there is effectively no chine to act as a stiffener .

John raises some very pertinent points about poor framing practices, in alloy this vessel is going to experience some early fatigue failure look at the fwd frame floor interface and the stiffener slot right on the interface, no knees or brackets.

Stu (Lazyjack) is correct too it's not robust enough and would have failed any society or survey inspection, as it will probably fail it's owner.

Not my design Raw, I'm probably guilty of the opposite approach. East coast Well promoted USA designer with a non engineering non boatyard background.

For Jeff's sake we'll leave it there.