Bottom or sides first

Any opinions on a hull fiberglass schedule on a wood skiff. Bottom vs sides first?
50” cloth is perfect to cover the bottom in one run. Then 1/2 the 50” cloth to do the sides.
Or another option is run a seam right down the center of the hull for zero side seams. Plan a grounding shoe so center seams would be protected. Hope some one with experience can help with this decision.

 

Lay the necessary laminate for the side all over the boat and then add, just on the bottom, the necessary layers to complete it. So first the side (+bottom) and then the bottom.

 

I usually do the bottom and sides, so that the chines get double glassing.

 

In this context the chines are part of the bottom. But why do you need double glassing the chines?

 

Because they are structural discontinuities and stress concentrations, as well as, in general, being subjected to high loads than elsewhere on the bottom owing to their limited area.
This is standard MO for any chine boat, no matter the material.

 

Thank you for your always professional and reasoned explanations. The latter has made me ask myself a few questions:
- Why are other "structural discontinuities and stress concentrations" of the hull not studied independently as, apparently, it is necessary to do with the chines?
- What are those loads, greater than in any other part of the bottom, that are applied to the chines?
- If we are talking about design pressure, how important is it that an element has a limited area? The design pressure is the same regardless of elements area.
- By treating chine as a natural reinforcement, and as a reinforcement it must be calculated, its area is not as limited as it might seem.
- If the chines have to double the laminate, what will have to be done on the keel?, quadruple? My MO (Modus Operandi, since Ad Hoc likes Latin) is that you don't have to double anything, but you have to calculate each thing correctly taking into account its particularities, and not add anything else.

Why would the loads applied to a hull depend on the material of the hull? Unnecessary explanation unless the subject we are talking about is unknown.
Once again, thank you very much Ad Hoc.

 

If you wish to learn and understand things that you do not know, it is always better to drop your polemic supercilious attitude and asinine comments.
This does you no favours and does not incline the person replying to assist you..
I thought perhaps 2022 you may turn a new leaf and drop you your attitude, but yet...here we are again...

You need to ask the designer of such vessels that do not pay attention to such details. Since to ignore these regions is negligent.

Stress = Force/area...... if the area is reduced, as it is on the chine... the stress goes up. It is rather elementary.

See above.

The calculate it... simple!

Even Class make reference to such regions by requiring and increase in localised plate thickness, so this is nothing "new" or surprising to those do structural design detailing.




As noted, even Class disagrees with you.

You are mistaken, it is INDEPENDENT of the hull material....it is understanding what the structure is doing and why and how to ensure it is fit-for-purpose.
Knowing what the material is, just reinforces what is already known and requires mitigation from: bending stress, shear stress, deflection and fatigue.

Very simplistically.

 

It's much simpler than all this designer nonsense - two layers on the chine for increased abrasion resistance where abrasion is most likely to occur.

 

One thing about glasswork to pay close attention to is you are not allowed to butt seam glass. And so overlaps, typically 2" are required.

And so, anyone needs to ask you whether overlaps are considered and where you have them planned.

The bottom of most hulls, needs to be flat as a pancake for less drag. And so, ideally, or for less fairing, the overlaps are best done on the sides. This is basic to the craft as a matter of course.

So, if the glass can overlap the sides not less than 2", I prefer 3", then that is ideal. And if your 50" glass cannot make the overlaps, then you generally consider seaming at the keel for easier fairing. Then, too, you would have been best off with 38" wide glass. I digress.

Another tip I will offer is using a sharpie to mark the glass is helpful if you are rolling the dry glass off on a wetted substrate. I can offer you lots of tips on glassing, but need to know the glass weight and a picture of the work will also help me see any potential problems. Certain weights of fabric do not wet down through well, including all biaxials.

A picture and the glass weight and I can help you better. You can private message the glass if you are worried about sharing intellectual property more broadly.

 

Here is a picture of a fellow who had planned to glass the bottom with a middle seam, but there are quite a few problems with his approach highlighted. Especially note what happens on the sides when you attempt to do a single go.

I advised him to overlap on the chines. Too often beginners get wrapped up in fabric savings. The way he has this setup would be a nightmare for a professional laminator. The area for an amateur is too large; the direction changes too many, the bunching is almost a guarantee to fail and this is db1200; the most forgiving fabric around. And glassing into the tunnel will create voids on cure because the layup will shrink on cure and lift.

 

Thanks all…question is answered. I got some heavy rolled resin paper and seamed it to 50” to try and answer this question. As Fall guys last picture indicated…I ran into this exact same problem of rippled drape.
Thanks again guys!

 

By the way…my 50” glass 2 1/2” up the sides at the skiffs widest bottom.

 

If you have any ripples you can't get rid of on the chine; you can razor blade them wet, but it isn't much fun. Good luck.