Osprey Sparrowhawk Project

[gotchiguy]

Originally Posted by Chris

The early ones were foam filled...

Interesting. I do remember reading that somewhere but I always imagined something along the lines of the bricks they put in catamaran hulls.

[1eyedjim]

bit of an update, dark nights are not helping but my spot light is helping no end,



winged back rest picked up from ed.



pic of the console



some photos of the damage to the keel after sanding back before reinforcing, i have decided to add a layer of glass to the whole hull as it flexed more that i liked, also will be adding duckting and bulkheads instead of the previous foam

[Searider]

Looking at the pictures of the inside of the hull I notice that there aren't any stiffeners - frames or stringers.

I wonder if the foam was originally intended to back up the hull shell structurally. Obviously you've commented that the hull flexed too much for your liking which may indicate that the foam had crushed a little.

I would have thouight that some form of structure would be needed under the floor.

[1eyedjim]

Yea. I spoke with mike Witham as I didn't want to have to use foam and suggested the newer models had bulkheads so will be fitting these at the next stage

[two stroke mick]

I have found that mike Witham is very freely helpfull and deserves any business he can be given.

[whisper]

Originally Posted by two stroke mick

I have found that mike Witham is very freely helpfull and deserves any business he can be given.

+1

[Searider]

Originally Posted by 1eyedjim

Yea. I spoke with mike Witham as I didn't want to have to use foam and suggested the newer models had bulkheads so will be fitting these at the next stage

A stringer either side too?

[biffer]

Looks so familiar, welcome to my world, first thing you need is a build spec, stringers, height, distance apart, bulkheads, fuel tank, underfloor trunking, deck fixing plates or strengthening plates, and blah blah blah, good luck

[1eyedjim]

Are stringers required as well as bulkheads? When I got the console and was talking to mike he just said to put bulkheads in. One 10in from the transom and then every 50cm from there

[biffer]

I would think that stringers were more important than bulkheads

[nugent]

Originally Posted by biffer

I would think that stringers were more important than bulkheads

What he says ,,

[1eyedjim]

Ffs now iv got to think again lol.

Few questions then

Do the stringers need to be one piece and run front to back?

Could I fit bulk heads in and then just run stringers in between these?

Do the stringers sit on the Chines of the hull so there would be two a side?

All the old sparrowhawks and eagles just ran with foam inside and they all seem to hold up fine. If I do both bulkheads and stringers is this going to be overkill?

Will there be any adverse effect due to the hull being so stiff after?

Sorry for the questions just helps when I understand a little more.

[nugent]

Originally Posted by 1eyedjim

Ffs now iv got to think again lol. Few questions then Do the stringers need to be one piece and run front to back? Could I fit bulk heads in and then just run stringers in between these? Do the stringers sit on the Chines of the hull so there would be two a side? All the old sparrowhawks and eagles just ran with foam inside and they all seem to hold up fine. If I do both bulkheads and stringers is this going to be overkill? Will there be any adverse effect due to the hull being so stiff after? Sorry for the questions just helps when I understand a little more.

I am not qualified to awnser this,

But if it was me two full length tied. Into transom with sandwiched knees ,, and a series bulkheads a max 750 ctrs would be my choice from 18mm Quality marine ply,,

Just to stop floor bouncing and to tye sides in,, But I am not a boat builder!!!

Biff was and is let him guide ya

[nugent]

Modern stuff is laminated foam shapes now
if concerned of weight being added but all that sodden foam would of been heavier for sure

[1eyedjim]

The foam was actually dry that came out. It only came apart so I could repair the hull properly.

[biffer]

It basically what Nugent said. We cut a rough pattern go the stringers out of 18 mm ply and bond two together with grp Matt. I say roughly because you have to think about floor level. I'm thinking if you're asking such basic questions as these this project is going to be a near vertical learning curve for you

[1eyedjim]

Tbh I didn't expect to have to go to this level when I got it. And after speaking to mike it didn't sound like an issue as was just bulk heads but stringers are not something I had thought about or even looked into

[matt h]

i would let an expert do it as Biff said or sort of said as that is a major job, I'm surprised they are like that.

[beamishken]

Surely if the later model boats only use bulkheads then that's enough? I'd assume the later boats have been tested thoroughly & if that's the spec then I'd be happy to go with what the builder recommends
Osprey are a fairly respected builder who have been about a bit
I can't see the point in overdoing things if you don't need to,
If mike is happy to assist with ongoing advice then there's nothing like the satisfaction in doing the job yourself

[Dirk Diggler]

Maybe later boats are built to a different schedule. I'd go with longitudinals every time, although some transverse structures as well aren't going to do any harm.