Petrel Play stripper, hull is fared and rough sanded. (Aside: the transition from unfared /unscraped to fared is nothing but astounding. It goes from chunky ugly to This Looks Like A Boat!). I’m weighing when to apply the outer stems in relation to glassing.
The instructions apply the stems before glassing; the videos show them going on after glassing. My inclination is to apply the laminated stem first, finish all the shaping/faring, and then apply glass I’m hoping for a single layer of glass for a light build (but there will be an extra stripe over the stem either way.)
The other is glass, then the stems, then one strip of glass over the stems. That only puts one glass layer over the stem. BTW, I’m planning on an epoxy skim coat before glassing, but that doesn’t impact this decision.
Yes, I’m completely over-thinking it. This is more of a “is there something I’m not thinking about?”
Thanks- Ari
Hi Ari,
as you mention, you can do it either way. and i have done it both ways.
if i was focusing on keeping it as light as possible, i would do the outer stems before glassing.
in this petrel play, that’s how i did it.
the main reason for doing it the other way around is if you are staining the hull dark and want a stem of natural color. it’s easier to get a clean line by locking in the dark stain on the hull with a layer of glass prior to applying the unstained stem.
h
You are so right about the transition after fairing the hull. I’m kind of embarrassed for anyone to see the rough hull, but after fairing I can just stare at it.
I’m curious as why you want to do a skim coat? And a related question, does doing a skim coat add weight in the end? I’m not advocating one way or another, just trying to learn.
Thanks for the quick reply. I’m not staining, so that’s not an issue. I’m even thinking I may glue the laminations on one at a time, or at least glue the first one down by itself, to avoid what could be a squid-wrestle of multiple slippery laminations all at once.
As to the skim coat, I took a strip-building skills course at Newfoundland Woodworks in New Hampshire ( great place for plans, boats, supplies, and classes, check them out.). We did a speed run build of a strip canoe in two days, so we put the glass on over sanded wood to save time. The instructor’s (Rose) recommendation for a beginner (me!) was to do a thin skim coat first. Because the dry wood will absorb epoxy, you’ve got to balance avoiding starved spots with over-saturation floating the weave. It’s one thing spotting and addressing those issues with a master craftswoman by my side, scraper in hand, as compared to me alone with the epoxy clock loudly ticking.
I also have three different woods on my boat - western red cedar, Alaskan white, and cherry. In my batch, the red and white cedars have very different properties, and the cherry is yet a different variable. My logic is that with a thin uniform base coat, I’ll be able to use less epoxy setting the glass, and will be able to sneak up on filling the weave in later coats. It’s all about limiting variables.
Because I’ve used some cherry, it’s less about a light build and more about not making it heavier where I can. This is going to be a lake boat so I can save weight by going with a single fiberglass layer. But it’s my first boat, so I’ll trade the weight of a skim coat against a potential glassing disaster.
i am a fan of skim coats for the following reasons
-
as mentioned above, if you don’t have a skim coat your epoxy is ‘competing’ for what will be absorbed by the wood and what is needed by the glass to wet out. so by seperating these steps, you can skim and seal the pores of the wood in a seperate step with only the minimum epoxy needed for the task…and then after that cures, seperately wet out the glass with epoxy. so two simple steps vs one step where you have an unknown (how much epoxy the wood will drink in the process) plus the wetout…which is pretty much known and not subject to variation.
-
skim coat seperate from wetout, as a result of the first reason, typically results in less overall epoxy because you can manage how much epoxy is applied in the skim coat.
-
the glass wet out step is easier becuase there is less epoxy that you need to apply…becuase you are only wetting out the glass…not also getting the wood to absorb the epoxy.
-
less potential for outgassing and bad glass work, becuase the open wood pores that can create bubbles or dry weave are sealed. that said, even with a seal coat i always try to apply in stable or slightly decreasing temperature profiles.
Thanks for the explanations.
Eliminating the outgassing bubbles is a really good reason. It plagued me on my first fiberglassing project. Had to go back and do a lot of remediation.
