caulking material ?? Arthur Edmunds

I bought a book "building a fiberglass boat" from American last week, the author is Arthur Edmunds .
Now I have many questions when reading this boat.
Look at the photos. I want to know what's the material of the caulking ?

 

Food for thought !

Caulking !! The material needs to be semi flexable as joins move , the material used also needs to be a adhesive and stick really well. fastingings have a habit of working loose over time . If its possible to glass join the hull to the deck then thats good but the glass used and how much needs to be carefully thought out . Make a small section of you deck and hull and do some own exsperimenting !!!. A polyester resin mix has been used by every boat company i ever worked at but recipies of the mixes vary consideribly some are good some not so good and others just plain silly. the top joins would be a better option over the lower one deck joins and beltings availible to use have to be very serously considered when making moulds . do some research and get samples .

 

My guess wood be 3M's 5200.

 

Woha no no not unless you never ever intend to remove it.

I think the world is a little short on suitable caulking compounds, something that is water resistant, mould resistant and does not shrink is all I ask.

I use sika flex but it is not mould resistant looking drab within a year.

I am at present feeling my way through industrial sika for construction, half the price and seems to be very similar and used for holding huge shop windows. It seems identical apart from the Marine prices.

 

I thought it was for gluing two halves of a boat together?

 

In some cases thats right just depends on the deck to hull joining system if its glueing its got to be better than just some muck out of a tube . neve found a squeeze slop thats suitable .

 

Ok so looking again Sikaflex left 5200 right.

 

3M 5200 and Sikaflex 291 are common for hull to deck joint. It isn't meant to come apart (refer to the drawing with the fiberglass tape in addition for the best joint; this is more labor intensive.)

Don't substitute a material without sufficient testing first - the cost of the proven marine adhesives is worth it for the piece of mind.

 

Sorry. yes if its to join a hull then 5200 would be the best.

Tunnels you need to try seperating 5200 it is almost a molecular bond that they say is not available on this planet but my god 5200 has to be close.

Removal is by mechanical means (it says on the tube) and they aint kidding.

 

There are situations where less expensive product less permenant is required.

I get mould on every caulking I use, soaking with bleach helps a bit.

Although 5200 and white sika is a good compound its cosmetic capabilities fail it.

 

With the hull to deck joint the adhesive sealant will be below a rubrail. Depending on the fit, it may be visible on the bottom of the rubrail where curvature is greater. This isn't an area of great visibility.
Rebonding a failed hull to deck joint is time consuming and messy.
A solid bond is increasingly important with thinner laminates and hull to deck joints which are nearer to the waterline with current styling.

 

The most important aspect of a deck joint is to seal the bulk heads from water..

A layer of glass and mat over the joint on the inside does not seal the bulk heads unless careful preperation has been taken.

 

3M-5200 usually isn't the choice most manufactures use, though it works, it's not as pliable as other choices. 3M-5200 can be separated, without damaging the faying surfaces, but prying and cussing isn't the way it's done. Heat works, as does a hot knife or rotary or multi tool.

Butyl rubber was once common for this joint, but now most use a polyurethane, but one more pliable then 3M-5200. This 3M product dries fairly stiff and everyone knows about it's aggressive adhesion. 3M-540 would be a better choice as would 3M-4000, both of which have a less aggressive adhesive, but more elongation. The deck cap/hull shell joint is best mechanically fastened, with a sealer insuring it stays water tight, just like the drawing shows in Edmund's book.

 

Silicone is a common sealer for that application. However, the practice of laminating the joint from the inside is, in my opinion, the best solution. Taking a deck off is not a common need unless the boat has major damage.

 

Many manufactures are now bonding the flange.