Wood vs Fibreglass

[PAR]

Wood is the hull build material that can tolerate the least amount of neglect. Again, I've seen 'glass yachts without a lick of care or upkeep for several years, yet they still float on their fouled and encrusted lines. Try this with a wooden boat and the marina will call you late one night, about how your boat has been moved to the service dock and a 5 HP Honda pump is keeping it afloat.

It's easily agreed that there isn't a perfect build material, but some are clearly better then others when it comes to the modern yacht owner. Gone are the days when an owner would religiously keep up a maintenance routine. Now, things are fixed when they break, fall off or a new, stylish one with blinking lights is available.

I'm having this discussion now with a client who wants a wooden 30'er, but knowing the upkeep his last boat had, I'm trying to convince him, 'glass is the only way for him.

[Wynand N]

Lets keep in mind that the thread starter wanted to build a 6m (18ft) runabout and for that purpose plywood - either molded or S&G method - would be perfect economically and ease of construction over GRP for a one off.

That said, with the outside covered with thin cloth and epoxy, faired smooth and painted, will look just as good as any GRP and be impervious to rot and any gremlins the sea/fresh water may offer.
And if I'm not mistaken, runabout usually means leisure boat with trailer and thus most the remarks made are pointless as the boat will be launched and at the end of day put back on the trailer...and if left on mooring for some time, the epoxy coated outside would provide all the protection needed.

[tunnels]

Name any material and it on the planet and it has its faults .
Only reason i choose glass is because i work with it every day of the week and month , i know what causes most problems other people have and its in my blood so to speak .
I fully understand what i can do and will do when i build a boat , so it will be just glass and vinylester resin thats my choice ,, No kevlar ,no carbon, no basalt , just glass and Foam core in places . Light strong yet flexable where it needs to be !!

[ondarvr]

Originally Posted by rwatson

These two conditions in the same 'sentence' convey the dilemma of boat owners. Gel coat does get very shabby over time - many people prefer an easily repaintable surface.

Fibreglass isnt the perfect material, any more than wood is - both are fraught with traps ( Rot V Osmosis ? )

You really have to set your priorities, like Tunnels - most people don't want to spend a lot of time and money on the perfect finish, while others cant love anything but perfection.

Gel coat is about the easiest surface to repaint there is, plus before painting it can brought back to life several times with a little elbow grease.

The other issue of osmosis (blistering). This can almost always be attributed to poor workmanship, or the wrong materials used. When the resin choice is based on price and not properties, and the workers chosen by the wages not the skills, then it comes down to the least suited qualities being found in both.

People compare mass produced glass boats built to a price point by people that just happened to show up that day, to custom one off wooden boats built by craftsman who love the type of boats they build and take pride in their work. Then determine wood must be better, although it still needs far more care to prevent problems.

Level the playing field with skill and raw material quality and the glass boats come out much better, they can survive a decade or two of zero maintenance and be serviceable without so much as a cleaning. This of course excludes the propulsion system.

No product is perfect, but skill and quality materials can make just about any of them successful.

[sabahcat]

Originally Posted by ondarvr

Gel coat is about the easiest surface to repaint there is,

No easier than a urethane topcoat.
In theory, the stuff I have on my boat can be wiped down with the appropriate solvent and resprayed.
At worst, a quick buzz with 180 grit and you are good to go

plus before painting it can brought back to life several times with a little elbow grease.

As can a urethane topcoat

The further advantage of a paint vs gelcoat topcoat is that the painted topcoat is considerably lighter.

Gelcoat is dead weight and a fair bit of it, which costs something to shift around and reduces vessel load carrying ability.

[ondarvr]

Originally Posted by sabahcat

No easier than a urethane topcoat.
In theory, the stuff I have on my boat can be wiped down with the appropriate solvent and resprayed.
At worst, a quick buzz with 180 grit and you are good to go

So it's not much different than gel coat, and at anytime gel coat can be painted too. Not all of the popular paints can be re-coated easily though.

As for weight...what are you going to fair the surface with before painting?

On a 1000 square foot surface there will be about 100 lbs of gel coat, paint and primer will come to a little less than a third of that, but only if no fairing is to be done. Let’s say paint, primer and fairing compound weight nothing, so you saved 100 lbs on 1000 sq ft

I don't dislike paint, and I use it, it has better UV resistance than gel coat and I would rather re-paint than re-gel coat.

Just need to be honest in the comparisons.

[sabahcat]

Originally Posted by ondarvr

As for weight...what are you going to fair the surface with before painting?

On a 1000 square foot surface there will be about 100 lbs of gel coat, paint and primer will come to a little less than a third of that, but only if no fairing is to be done. Let’s say paint, primer and fairing compound weight nothing, so you saved 100 lbs on 1000 sq ft

Any gelcoated boat I have cut into has had between 3 to 5mm of gelcoat, which is high solids and heavy.

The majority of composite ones I have done have had 3mm and LESS of lightweight fairing compound, followed by a few microns of primer and paint.

Also, the nature of the beast with a composite boat means that the structure is considerably lighter as well, Balsa, foam, light timber core and considerably less skin thickness than a solid glass boat all mean that the weight savings are immense.

[hoytedow]

Originally Posted by gonzo

If you build a wooden runabout, alkyd enamel will do fine. I think I am of the boatasaurius species like PAR

Me same.
Number 1 boat just plywood, iron screws and cheap oil paint.
It great fun.
Ugh!

[ondarvr]

Originally Posted by sabahcat

Any gelcoated boat I have cut into has had between 3 to 5mm of gelcoat, which is high solids and heavy.

The majority of composite ones I have done have had 3mm and LESS of lightweight fairing compound, followed by a few microns of primer and paint.

Also, the nature of the beast with a composite boat means that the structure is considerably lighter as well, Balsa, foam, light timber core and considerably less skin thickness than a solid glass boat all mean that the weight savings are immense.

Gel coat is recommended to be in the 18 to 20 mil range, that's .02 inches or
.508 MM...any gel coat that is in the 3-5 MM range would have well beyond what is recommended or needed, it in fact would have been applied totally wrong. 5 MM is closing in on ¼”.

[ondarvr]

Originally Posted by Wynand N

Lets keep in mind that the thread starter wanted to build a 6m (18ft) runabout and for that purpose plywood - either molded or S&G method - would be perfect economically and ease of construction over GRP for a one off.

That said, with the outside covered with thin cloth and epoxy, faired smooth and painted, will look just as good as any GRP and be impervious to rot and any gremlins the sea/fresh water may offer.
And if I'm not mistaken, runabout usually means leisure boat with trailer and thus most the remarks made are pointless as the boat will be launched and at the end of day put back on the trailer...and if left on mooring for some time, the epoxy coated outside would provide all the protection needed.

I had one of these as a young kid when we lived on an Island, I glassed the hull when I was 10 or 12 years old and it lasted through many years of use.

[sean-nós]

My first runabout is plywood coated in 6oz cloth and I was able to get a great finish on the paint with a lot of prep.
The one I'm building now has 4oz cloth clear finish over mahogany planks on the sides and 6oz on the bottom. You can see them below