Putting stringers where there haven't been any until now...

[NickNap]

After 39 years the cabin floor has become saggy, - so I decided to cut it out & replace, putting stringers in to support the new section. There are no stringers currently, and about a 3" gap in the centre, going to nothing as it meets the hull at each side of the floor (where the moulding is bonded to the hull & goes vertically to form the locker/seat bases)

However, in the West system booklet section on epoxying in stringers, there's a caution about putting them where there weren't any before, causing stresses in an area that used to be able to flex.

She's a 1972 Westerly Pageant. I've removed part of the floor and can confirm the hull does flex a bit if I push down firmly through where the gap in the floor is.

What do the team think? Stringers or a stronger self-supporting floor section?

 

[gljnr1983]

I would say sticking stringers randomly in the middle of a flexable panel is a no no but taking them from a non flexable point across the flexable then onto solid stuff again would be better with pleanty of matt tapering out from the stringer base.

 

[sailorman]

After 39 years the cabin floor has become saggy, - so I decided to cut it out & replace, putting stringers in to support the new section. There are no stringers currently, and about a 3" gap in the centre, going to nothing as it meets the hull at each side of the floor (where the moulding is bonded to the hull & goes vertically to form the locker/seat bases)

However, in the West system booklet section on epoxying in stringers, there's a caution about putting them where there weren't any before, causing stresses in an area that used to be able to flex.

She's a 1972 Westerly Pageant. I've removed part of the floor and can confirm the hull does flex a bit if I push down firmly through where the gap in the floor is.

What do the team think? Stringers or a stronger self-supporting floor section?

what you propose wont be structural will it, only sole board supports

 

[Bosun Higgs]

However, in the West system booklet section on epoxying in stringers, there's a caution about putting them where there weren't any before, causing stresses in an area that used to be able to flex.

Do it the other way round - attach the stringer to the underside of the floor panel. Or even make the stringers so that they dont have to be bonded.

 

[30boat]

I wouldn't worry too much about that.What flex there is was not engineered in and you can always benefit from a stiffer bottom in the way of the keel.Westerlys are known for poorly reinforced bottoms anyway.

 

[William_H]

Flexing

The engineering concern for stiffness being added to a flexing structure is perhaps easily demonstrated by an example of an archery bow. It relies on flexing equally across the bow. If you stiffen one part of the bow you get greater bend at the remaining parts. So if a hull section must flex and you stiffen a small part then the remaining parts must bend more.
I think by comparison if you stiffen the whole bottom sideways then you will not produce a hard section provided of course that it is not flexing front to back. If that is of concern then a stringer front to back might solve the problem. Or put simply partial reinforcement can be trouble total reinforcement no prob. good luck olewill

 

[Scotty_Tradewind]

A 1972 Westerly is built so strong I cannot see the stresses being any problem.
Have you an owners Ass' club to advise?

A modern boat may be an different matter.

 

[Poignard]

Nick

There's a book I remember looking through years ago that had advice on how to strengthen a grp hull. I think it was called 'Upgrading the Cruising Sailing Boat

http://www.amazon.co.uk/Spurrs-Guide-Upgrading-Cruising-Sailboat/dp/0071455361

Might be worth a look.

 

[Scotty_Tradewind]

Nick

There's a book I remember looking through years ago that had advice on how to strengthen a grp hull. I think it was called 'Upgrading the Cruising Sailing Boat

http://www.amazon.co.uk/Spurrs-Guide-Upgrading-Cruising-Sailboat/dp/0071455361

Might be worth a look.

Thanks P'..... a few 2nd hand ones available from around £10 Just the sort of thing I may find useful too.
one on order
S.

 

[NickNap]

Thanks guys, as ever, good advice to take away. Will go for that book too
cheers
Nick

 

[Scotty_Tradewind]

Nick

There's a book I remember looking through years ago that had advice on how to strengthen a grp hull. I think it was called 'Upgrading the Cruising Sailing Boat

http://www.amazon.co.uk/Spurrs-Guide-Upgrading-Cruising-Sailboat/dp/0071455361

Might be worth a look.

Good book for a lot of general ideas and info', thanks, arrived yesterday from Amazon
Spurr's Guide to Upgrading Your Cruising Sailboat