How to make a hull in epoxy and fiberglass only from a mold — no vacuum

Every aspect of the build is adjusted or changed depending resin type, fiber type, and how you plan to use it.

As has been mentioned, you need to fully understand what you plan to do with it, then find someone qualified to engineer the design and build.

There are no real unknowns in this other than your skills, the marketplace has many experts that can tell you exactly how to build it, and what materials to use.

 

Actually here where I am there is nobody who work with epoxy, hence this thread…

The whole subject of this thread is about to know how to make such hull in epoxy and fiberglass only.
That is which kind of fiberglass should be used:
— thick and few layers or thin and many layers (I heard the hull is more stronger if laminated with many layers of thin fiberglass: is it true?)
— using biaxial or quadriaxial or…?
— what the correct epoxy should have displayed on its packaging / technical information?
… this kind of things.

The most experts you can find here where I am who make boats in factories since decades even don’t know that fiberglass used for polyester resin have a binding agent that epoxy resin do not dissolve and therefore an adapted fiberglass is needed to work it with epoxy. And even here on this thread it seems that some are not aware that there is this issue when working with CSM (chop strand mat)…
There is suppliers here who sell fiberglass saying it suit «polyester, vinylester, epoxy» I don’t trust them. They can be just foolish people not knowing anything about it but just wanting to sell their products. Therefore it is always good to get informations about this topic. Some informations can make a big difference when purchase products. Such as «if they don’t speak about powder binding agent suitable for epoxy, it may be that they just don’t know».
(suitable binding agent for epoxy is not necessarily in the form of powder, but normally powder binding agent is made for the CSM to be compatible with epoxy resin. For information polyester contain styrene that dissolves binding agent of CSM which 1) allow polyester to access to the fibers 2) to let the fibers to be bended to the desire shape).

 

In a typical epoxy build no CSM is used, there is no need for it.
It's strictly stitched or woven fabrics. An epoxy laminate schedule might be similar to a polyester one, but would eliminate all of the CSM and resin associated with it, so maybe 1/3 less in weight. But the exact fabrics used in what order for something you plan to sail the oceans with should be engineered, not guessed at.

 

After 47 posts, we have 'still' not seen a photo (or any drawings) of the mould for the 19' boat that Space wants to use - are you still planning on using this mould?

Here is an excerpt from your original post :
------------------------------------------------------------------------------------------
I have a good female mold I can use to make a 19 feet long hull (mono-hull).
This mold is normally used to make fiberglass and polyester resin only hulls.
To make it stronger and durable I want to make it in epoxy and fiberglass only.

Believe it or not I can’t find any resources to help me doing it this way!
I can find only resources about how to build with polyester or wood covered with epoxy and fiberglass.
Any help is therefore much appreciated on this project.

The boat must be strong enough to survive any storm, hurricane, rogue waves, capsizings…
It will be a sailboat that will sails all oceans. Of course a deck will be add also in fiberglass & epoxy and the shape & ballasts will make it self-righting.

I will build it the simple way: no sandwich construction, no vacuum infusion technique.
I just want to lay down sheets of fiberglass and laminate epoxy with a paint / metal roller on it.
The boat hull may just be a layer for the hull and reinforcements beams also in fiberglass & epoxy in square shapes.
This beams shape are named «hat stiffener with hollow former» on this page: Fishing boat construction: 2 Building a fibreglass fishing boat https://www.fao.org/3/t0530e/T0530E08.htm
--------------------------------------------------------------------------------------------------------

Are you basically looking for an effective and efficient laminate schedule for building this 19' hull out of single skin fibreglass using epoxy resin?
If so, then some more info about the hull / mould would be useful.
For instance, will it have an encapsulated keel, or a bolt on keel - or maybe twin keels, or a centreboard?
The laminate schedule for the hull bottom would be different for each of these different types.

Will the mast be deck stepped, or will it go through the deck down to a step on the keel?

What type of superstructure will you put on this hull?

 

Ondarvr thank you for this informations.
I heard mainly that csm should always be at the outmost layer and in between layers of woven fabrics. But two days ago I read about someone advising to use csm only for the outmost layer only, not in between. So far all this possibilities has been said… without enough explanations to justify which method to use instead of an other one. And therefore I don’t know what to do.

So far the explanations I know to use csm in between is for the strength of the hull, since woven fabrics are here more to respond to forces in movements of the hull interacting with the sea.

By the way one youtube video just released speaking about different waves length, he igh and frequencies as I told before:

Bajansailor I will not post any plan or pictures of my boat since it is irrelevant.

 

Suit yourself, if that is your opinion.

Why are you so adamantly against posting any information about the boat / mould itself?

This is basically correct if you are using polyester resin.
But I think you want to use epoxy.....

What does this reference suggest that you do then - are they implying that you should lay up woven rovings on top of each other, with nothing in between?

 

The only reason for CSM as a skin in an epoxy build is you can more easily get a better cosmetic finish. It may have fewer surface defects and gives you something to sand into that isn't structural. There is no need for it between layers of woven or stitched fabrics.

CSM plays a key roll in polyester and VE hand laid laminates, but not in epoxy laminates.

 

— obvious reasons. No one here will do the work of a naval architect just for this boat. General principles is what I am looking for and will be usefull for future reader of this thread.
Better to explain what should be done in the case of a single keel, in the case of a double keel than just stick to one design.
What I said so far concerning my boat is enough.

— why? The idea of CSM bringing strength sound true. I see no reason why it should be different when using epoxy.

— yes that’s what have been said. You do use a csm for the external layer since it will provide the smoothest surface compared to woven fabrics.
If you use a woven roving layer as the outmost layer of the hull or the deck or whatever it will show relief of a cloth. One can also use a very thin woven roving instead.
I guess this is what they do on surfboards.
But csm is supposed to bring stiffness so better in that case to use csm: the stronger the boat the better.

 

Ondarvr your post released right before mine so I answered bajansailor before reading it.
Doesn’t chop strand mat bring strength to the hull even with epoxy?

 

Just to briefly mention that woven/biax/trax/quadrax are all well suited to hulls that have developable surfaces.If you hull is a curvaceous round bilge type,with a fuller type of bow,you will have to tailor it to the shape.Whether this information is going to a potential builder or a server gathering information for an AI business is something I can't be sure of, given the reluctance to post pictures.

 

The AI thing is ridiculous but thanks for this answer.
So you say the more curves and «details» the mold have the harder it will be for fabrics such as quadraxial to conform to the shape of the mold, right?
It makes sense. But is it the only reason that would drive one to use per instance biaxial rather than quadriaxial?

 

Not really the only reason,any fabric will present the same challenge and will need more care in fitting to the shape.CSM has fibres that cam move more readily as they are not anchored in position and this makes it simpler to mould complex or highly curved parts.The most useful aspect of stitched fabric is that the fibres can be aligned with the loads in the region and will resist stretching more effectively,but in reality it takes a fairly specialised boat to reach the performance level where this is a factor.for something that is intended to travel far and successfully there is likely to be so much weight on board that a less sophisticated laminate,and quite a lot of it,will be a less risky way to produce the hull.If we are considering a displacement hull that has a hefty ballast keel and several months worth of food and water,it won't be a flyer.

 

Good. Nice to know.
How thick a hull in fiberglass and epoxy would you recommend then?
What fabric would you recommend?

 

No, CSM is considered a waste of money and time in an epoxy laminate due it really adding nothing but weight, it sucks up a large amount of epoxy with little benefit. If more strength is desired, use another layer of stitched or woven fabric. The glass to resin ratio will be much better too.

In-mold the CSM first layer may have a slight cosmetic advantage, but doesn’t add anything structural. It's considered a sacrificial layer for sanding purposes.

 

Nobody can give you a laminate schedule without knowing the exact hull design and how it will be rigged, that was already mentioned. We seem to be running in circles here.