cheapest wide beam shell with engine

[boatgoball]

anyone out there reccomend a boatbuilder who can build me the cheapest possible no frills 14ft x 60 ft widebeam shell with an engine

[blackrose]

anyone out there reccomend a boatbuilder who can build me the cheapest possible no frills 14ft x 60 ft widebeam shell with an engine

 

14'? I'm not sure... Liverpool Boats do a 12' x 60' and they might make a 14'?

 

12' is plenty wide, are you sure you want 14'? Where do you plan to be moving it?

 

I met a bloke on a 14' x 70' widebeam on the Thames a couple of years ago - that's a massive space.

Edited February 25, 2007 by blackrose

[John Orentas]

14'? I'm not sure... Liverpool Boats do a 12' x 60' and they might make a 14'?

 

12' is plenty wide, are you sure you want 14'? Where do you plan to be moving it?

 

I met a bloke on a 14' x 70' widebeam on the Thames a couple of years ago - that's a massive space.

 

 

Fourteen feet must be seen as a bit dodgy, certainly you would not get through the Rochdale for a few years, some of the locks have been squeezed so much that two 6' 10" narrowboats can't share and I think there are many other canals in a similar condition.

[Gary Peacock]

A cheap 14' is going to be difficult the engineering alone makes it expensive. I don't know of many builders who will get involved at that size it's not really a project for the under the railway arches brigade and if you were to just build a fat narrowboat at 14' it would be even more hilarious where the regulations are concerned then some of the 11 and 12' offerings you here about.

 

 

 

This was the last 14' sail away we did last year there are a few more pictures HERE it's only 50' long but it's a very spacious boat even at that.

[blackrose]

Gary, at what centres are the cross beams on that barge? From the photos it looks like about 2'?

 

I was talking to Chris Polley about this - how come a 12' or 14' beam receives so much attention in terms of bracing yet the 50' or 60' length receives none? It just relies on the strength of the sides? Surely a wave hitting the bow will cause the hull to flex along its length?

Edited February 25, 2007 by blackrose

[Gary Peacock]

Well that boat is Cat D so waves aren't really supposed to come into it much also that boat is peculiar in that it uses a narrow base plate and a fold in the side sheet to form a chine and it's just under 50' so it's a bit of a oddity really.

 

The steel spec on that boat is 15/8/5/5 increasing the steel spec is a fairly simple way of achieving compliance while still leaving a sensible panel size the gap between bearers this for CBA members is now dictated by the software package they are now expected to comply with that actually pushes the specs beyond the RCD requirements.

 

If you add a longitudinal girder this effects panel size and the calculations but without it's geometry is large it does not add the strength you would assume the software model that the CBA's software generates often means that the geometry of the other angle and box used in the build now need to vary from what used to be the old excepted standards.

 

If you fancy an experiment and you know the methods used and dimensions of your hull we could run it through the software and see what it comes out like.

This isn't really the thing I get involved with but I think I can just about "drive" the software enough to get some figures out of it!

 

Now if someone else would like a go at doing it manually too that would also be very interesting to see how the results compare, the software is supposed to be good but I for one aren't capable of doing it by hand!

[blackrose]

Well that boat is Cat D so waves aren't really supposed to come into it much also that boat is peculiar in that it uses a narrow base plate and a fold in the side sheet to form a chine and it's just under 50' so it's a bit of a oddity really.

 

The steel spec on that boat is 15/8/5/5 increasing the steel spec is a fairly simple way of achieving compliance while still leaving a sensible panel size the gap between bearers this for CBA members is now dictated by the software package they are now expected to comply with that actually pushes the specs beyond the RCD requirements.

 

If you add a longitudinal girder this effects panel size and the calculations but without it's geometry is large it does not add the strength you would assume the software model that the CBA's software generates often means that the geometry of the other angle and box used in the build now need to vary from what used to be the old excepted standards.

 

If you fancy an experiment and you know the methods used and dimensions of your hull we could run it through the software and see what it comes out like.

This isn't really the thing I get involved with but I think I can just about "drive" the software enough to get some figures out of it!

 

Now if someone else would like a go at doing it manually too that would also be very interesting to see how the results compare, the software is supposed to be good but I for one aren't capable of doing it by hand!

 

Plenty of waves on the tidal Thames - it's still Cat D territory. I hit a few that must have been 1m high.

 

Anyway, my boat is Cat D, 57' x 12' (unchined) with cross girders and side struts at 2' centres. The baseplate is 10mm and the sides are 6mm. I'd just be interested to know if it conforms. If not at least it floats!

Edited February 25, 2007 by blackrose

[John Orentas]

Plenty of waves on the tidal Thames - it's still Cat D territory. I hit a few that must have been 1m high.

 

Anyway, my boat is Cat D, 57' x 12' (unchined) with cross girders and side struts at 2' centres. The baseplate is 10mm and the sides are 6mm. I'd just be interested to know if it conforms. If not at least it floats!

 

 

I think we would need a lot more than a one metre swell to damage 6mm plate and yachty types say that a 3: 1 or 4: 1 beam to length ratio is about right.

 

I remember looking at a beautifull 50 foot steel yacht at the boat show a few yeas ago, it was built from 5mm plate throughout, not too much framing either.

[blackrose]

I think we would need a lot more than a one metre swell to damage 6mm plate and yachty types say that a 3: 1 or 4: 1 beam to length ratio is about right.

 

I remember looking at a beautifull 50 foot steel yacht at the boat show a few yeas ago, it was built from 5mm plate throughout, not too much framing either.

 

Yes, I'm not talking about damage so much, but I can't understand why builders put so much reinforcement across the beam of a boat yet none down its length? I'm not questioning the correctness of this, just trying to understand it.

[ChrisPy]

Yes, I'm not talking about damage so much, but I can't understand why builders put so much reinforcement across the beam of a boat yet none down its length? I'm not questioning the correctness of this, just trying to understand it.

the magic 'beam strength' comes into play. The hull side acts as a web of a deep beam and the bottom plate acts as a wide flange - providing it is stiffened. That beam, if it can't collapse, has enormous strength in a swell. But athwartships the only strong 'beams' are at the full bulkheads. I suppose a good corollary is a shoe box - as long as the sides don't collapse the box is quite strong lengthwise, but it has little strength against a force slamming into the bottom every few seconds.

 

does that help the visualisation?

[blackrose]

the magic 'beam strength' comes into play. The hull side acts as a web of a deep beam and the bottom plate acts as a wide flange - providing it is stiffened. That beam, if it can't collapse, has enormous strength in a swell. But athwartships the only strong 'beams' are at the full bulkheads. I suppose a good corollary is a shoe box - as long as the sides don't collapse the box is quite strong lengthwise, but it has little strength against a force slamming into the bottom every few seconds.

 

does that help the visualisation?

 

Mmm.. the shoebox analogy. Yes, as long as the sides don't collapse!

[carlt]

Mmm.. the shoebox analogy. Yes, as long as the sides don't collapse!

 

Wouldn't the cheapest possible, no frills wide beam shell have similar lines to a shoe box?

[John Orentas]

the magic 'beam strength' comes into play. The hull side acts as a web of a deep beam and the bottom plate acts as a wide flange - providing it is stiffened. That beam, if it can't collapse, has enormous strength in a swell. But athwartships the only strong 'beams' are at the full bulkheads. I suppose a good corollary is a shoe box - as long as the sides don't collapse the box is quite strong lengthwise, but it has little strength against a force slamming into the bottom every few seconds.

 

does that help the visualisation?

 

 

That six inch reverse of the gunwhale is massively important too, easy to anticipate in hindsight but my builder accepted the job of building a full length resturaunt boat, the chap wanted maximum 'shoulder width', so only an inch or so of gunwhale, even with the cabin fitted it was like a wet dish-cloth, needed tons of extra stiffening and extra knees to keep the sides straight.

[blackrose]

Wouldn't the cheapest possible, no frills wide beam shell have similar lines to a shoe box?

 

And be manufactured from a similar material

[ChrisPy]

That six inch reverse of the gunwhale is massively important too, easy to anticipate in hindsight but my builder accepted the job of building a full length resturaunt boat, the chap wanted maximum 'shoulder width', so only an inch or so of gunwhale, even with the cabin fitted it was like a wet dish-cloth, needed tons of extra stiffening and extra knees to keep the sides straight.

you're right John, the gunwale return acts as the top flange of the beam, also helping to stabilise it against collapse.

[Gary Peacock]

Anyway, my boat is Cat D, 57' x 12' (unchined) with cross girders and side struts at 2' centres. The baseplate is 10mm and the sides are 6mm. I'd just be interested to know if it conforms. If not at least it floats!

 

OK we will work through the scantlings software then. Now I don't normally get involved with this so this could be a bit of a learning curve for everyone!

 

 

The software was developed by Dr Robin Loscombe PhD C.Eng FRINA of Southampton Solent University so please don't moan at me if you don't like or disagree with how it functions!

 

So step 1

 

 

So first of all you need to provide me with the information to insert in A - N the examples shown are obviously for a narrowboat.

 

 

Oh I can just imagine the guy who builds boats under the railway arches bothering with this can't you!

[blackrose]

Well, if he only has to do it once for each type or size of boat he builds it doesn't seem too much trouble.

 

My measurements are:

 

A: 17.37m

B: 12m

C: 2.74m

D: 15.84m

E: 10.66m

F: 2.74m (what's the difference between F & C?)

G: 12.19m

H: 1.25m

I: 0.6m

Stern is immersed by about 0.038m

J: 3.50m

K: 3.65m

L: 1.21m

M: 0.6m

N: 3.65m

 

Some of these are approximations.

Edited February 26, 2007 by blackrose

[John Orentas]

"The software was developed by Dr Robin Loscombe PhD C.Eng FRINA of Southampton Solent University so please don't moan at me if you don't like or disagree with how it functions!"

 

I'm always a bit sceptical about these academics and their computer models, I would like to know why they also need those test tanks facilities at the cost of millions of pounds, model ships zooming up and down in them.

 

P.S. Let's not be too scathing about railway arch builders, I tried to buy a shell from Gary Gorton some years ago, he would have considered a railway arch to be 'state of the art luxury'. When I eventually found his place it was a field, one garden shed for storage and a couple of WW2 diesel welding sets, but from that patch of ground emerged some of the best boats I have ever seen.

Edited February 26, 2007 by John Orentas

[Gary Peacock]

Well, if he only has to do it once for each type or size of boat he builds it doesn't seem too much trouble.

 

My measurements are:

 

A: 17.37m

B: 12m

C: 2.74m

D: 15.84m

E: 10.66m

F: 2.74m (what's the difference between F & C?)

G: 12.19m

H: 1.25m

I: 0.6m

Stern is immersed by about 0.038m

J: 3.50m

K: 3.65m

L: 1.21m

M: 0.6m

N: 3.65m

 

Some of these are approximations.

 

 

Right when I get a bit of time I will make a start on that.

 

I think the F & C bit is about the way the hull is split into upper and lower (Immersed). So F is over all and C is from the waterline. (I think!)

[Gary Peacock]

Ok I have those figures entered so the next information I need is:-

 

 

1. What is the base plate framing arrangement Transverse Frame only, Transverse Frames plus one same depth centreline girder or Two girder, no frames?

2. What is the frame spacing?

3. How are the frames attached to the hull sides?

4. How much does the boat weigh roughly I guessed around 26 tonnes.

 

This is the idiot guide for this section.

 

For the next bit after this we will need to know the geometry of the frames used.

[blackrose]

1) Transverse Frame Only (plus frames on the sides)

 

2) 2' (0.60m)

 

3) Don't know? I guess they're welded (Chris?)

 

4. I thought it was 26 tonnes too but from the displacement thread I calcluated 30 tonnes.

Edited February 27, 2007 by blackrose

[ChrisPy]

3) Don't know? I guess they're welded (Chris?)

As far as I recall, the bottom diagonal corners of the bottom stiffeners are cropped to provide a limber hole at each end (to let water by). the bottom stiffeners are welded to the side frames.

[magnetman]

How are the frames attached to the hull sides?

Is this a question of whether they are stitched or continuously welded, don't know if that makes any difference but thats what I see in the question.

Or they might have accounted for rivetting or bolting but I doubt it.

[Gary Peacock]

How are the frames attached to the hull sides?

Is this a question of whether they are stitched or continuously welded, don't know if that makes any difference but thats what I see in the question.

Or they might have accounted for rivetting or bolting but I doubt it.

 

Normally they would be sniped and welded directly to the side sheet or to the vertical side frame it sounds like these are spot on, the concern is if they are not attached at the ends but simply cut short in which case they only serve to support the floor and the full base plate would become one large panel at which point you can probably forget about any compliance.

[magnetman]

Normally they would be sniped and welded directly to the side sheet or to the vertical side frame it sounds like these are spot on, the concern is if they are not attached at the ends but simply cut short in which case they only serve to support the floor and the full base plate would become one large panel at which point you can probably forget about any compliance.

Oh right, thanks for the explanation.