Molded Interior: Fiberglass/Wood interface

[drjohn71a]

If cutting a hole in the existiing fiberglass in order to attach wood is so difficult, you could take the boat to a fiberglass shop and have them cut the hole, I guess. How do you guys attach accessories to your FIBERGLASS boats if you can't handle drilling or cutting a hole into it?

John

[drjohn71a]

Warren - to answer your question about drilling a hole in fiberglass:

1 - probably nothing more than a face mask, unless doing alot of holes.

2 - if the holed area has wood core inside, you overdrill the hole size, put filled epoxy putty (easier to redrill than solid), and re drill the hole after that sets. For small bolts/screws, I just predrill the holes work epoxy paste inside (line the hole walls) using tiny brushes, toothpicks, pipecleaners, whatever, then put the screws in that IF NOT EXPOSED TO THE WEATHER.

3 - Passagemaker's last issue has a detailed breakdown of how to best install things into cored hulls.


Also, you can "hollow out" the sandwiched wood core by putting a bent hangar wire (small "L") thru the fiberglass hole in a hand drill. That undercutting removes damaged core and allows space to put the filled epoxy before redrilling. that way a leak thru the bolt would not be able to get into the wooden sandwiched area.
John

[Sea Wolf]

C-Brats All-

This discussion has yielded some interesting ideas on how to interface new wooden or composition modifications with molded fiberglass interiors, and Dr. John has done a creditable job to champion their cause!

However, it would appear that modifing a fiberglass interior is just fundamentally more difficult than a plywood one due to the hardness of the fiberglass, the very sharp and specialized tools needed, the hazardous waste produced, the difficulty in removing the waste, and the more difficult joinery usually required to attach the new wood material to the fiberglass.

Additionally, the molded fiberglass panels may be permanently bonded or otherwise difficult to remove, making working on them with more accurate stationary machines out in the shop difficult or impossible. This results in the use of, for the most part, hand power tools which are harder with which to do very accurate work.

Another aspect of this process is that fiberglass is more difficult in which to fabricate new parts when they or a composition material is required. Learning and practice can go a long ways in making one more comfortable with these building processes, but the combining of materials, the resin set-up and cure, and the mechanical bonding process during fabrication are simply more complicated to master.

Lastly, the wood to fiberglass joinery interface is asthetically somewhat more difficult to do, as dissimilar materials are being joined. The results, however, can be very beautiful and pleasing to the eye.

As an addendum, we have also seen that Iggy's original proposition that most of us are less familiar with working with glass than wood is a complicating factor that stymies the process of customization.

I'm not complaining here, just trying to summarize and bring together what we've found out together, adding a few thoughts in the process.

More ideas to consider?

Joe.

[thataway]

I love to work with wood--nothing more satifying than a hand chizzel. But Fiberglass is not all that bad either--I agree about the dust and itch--but try building a 38 foot boat! When doing serious fiberglass cutting or laminating, I wear a Tyvek suit. These are disposable and inexpensive. They are hooded. I also wear a good quality respirator, as well as googles. I also always wear nitrile gloves and put a barrier cream on the arms. Many of my friends who build composite boats use full suits with full displacement respirators.

However for drilling a hole, I just use a regular drill. I often use hole saws, and have from 5/8" up to 4" in my tool kit by about 1/8" sizes (some 1/16"). I also have sanding drums to enlarge holes. I use carbide tipped saws. For example a year ago I cut about 50 sections out of 20 wrecked boats for a project--all of this with a battery and 110 volt skill saws with carbide blades--the blades not the worse for the wear. (most had cores so the glass was not real thick). I also use bimetal saber and sawzall blades. They have to be changed regularly. Recently I have been using a rotozip--I tried one a few years ago--and the new ones are much better. (use a carbide blade). I also use a Dremel tool (own a number) with various carbide blades. Also a cutoff wheel and grider is used frequently. All are very agressive tools. Another tool is the Fein saws Not cheap, but can make fine cuts and are excellent tools.

As for building up; or adding, I prefer epoxy. Some are allergic to it so be cautious. Also one needs to be sure that the cloth used is compatable with epoxy (the sizing may be different than polyester resin compatable).
I often "stick" wooden blocks on glass surfaces to allow me to screw items to them. For example I was asked how I attatched the foreward window fans recently. I shaped a wooden block to the contour of the piller and after sanding the gelcoat, applied fast set epoxy and taped the block in place.

When cutting, I do remove upholustry, use tape and plastic to limit the dust. I often cover an area to be cut with duct tape to prevent scarring the edges.

I agree that most of what one modifies inside of a boat is to cut out areas and then put in wooden doors and shelves. However I would not put in a wooden shell to just screw to; this adds excess weight. It is easy to epoxy in cleats (wooden to fasten shelves to), or add "L" brackets to bolt or screw to.

When drilling a hole in gel coated area, start with the drill in reverse, or use a counter shink to cut the outer gel coat away and avoid cracks.

When cuttin holes in cored materials, always bore the hole oversize and coat the inside with epoxy (not polyester). The epoxy gives a much better secondary bond and prevents water intrusion into the core. You may have to use a small drum sander or drill to smooth and bring the hole up to the size you need.

I rarely vacuum bag items--this is more in using exotics or very compact laminates--it is a wonderful technique.

Fiberglass interiors have been around for along time--and I have owned both wooden and fiberglass interiors--either can be worked with and modifications made. I would not decline to buy a boat because of the glass molded interior. I have also done radical modifications of the exterior of boats--cutting a transom, putting in steps, putting in cockpit seats etc--all of this is fairly easily possiable--but there is a lot of detail work.

It is hard to know where to stop in discussion of techniques--but I am happy to attempt to answer any specific questions.