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Transition from varnished hull side to the underwater area
My Name is Volker Bartoniczek I am from Germany and I was following the Varnishing course with great interest.
Unfortunately, the focus on 1 component varnishing was quite contrary to my plan for the varnish build up.
Still, I got a lot of ideas and details from the course. Thank you very much for that.
I am currently building a boat from scratch using cold molding technique. The construction and multiplex layers are ready now and I started laying the mahogany veneer.
So, it is actually still top down but I guess it is a good point in time for planning the buildup of the Varnish and underwater paint area.
This brought me to a question that was not addressed in the course.
What is the best way to handle the transition from the hull side of the boat to the underwater area?
My plan:
- Apply fiberglass to the bottom.
- 3 coats of epoxy on the entire hull
- mask waterline
- Paint the underwater area.
- Apply 6 coats of Epiphanes PP to the side of the hull side up to the waterline. Let the hull side rest while building the deck
- Flip the boat and build the deck
- apply another 10-15 coats of varnish
My key question is how do i handle the transition from the varnish to the underwater paint????
As more coats of varnish are applied to the hull side, it would create an edge at the waterline, which I'm sure is not desirable.
How have you solved this in your projects? do you have a good suggestion for me?
Thanks for any helpful hint on this.
Hi Volker, great to hear you are enjoying the course.
Epifanes PP will be a great move for your boat, I use it almost all the time these days for anything that needs volume building. The Stapley I work on in the project spotlights module uses this system with epoxy as a base. I have recently started back working on this boat again and will post the next video in the series soon where I will finish off with 2 part polyurethane clear. This should be a good guide for you to follow. All the other prep and application techniques from the course will remain the same.
Great question on the waterline point. The way that I tend to approach this is by adding a boot stripe line into the finish; a small line that covers the transition between the varnish and bottom paint. I usually brush it in with a yacht enamel. This allows you to feather out the differing film thicknesses between bottom paint and varnish and also to cater for the fact that this line is likely to wander slightly over the course of the project with the various masking sessions. The boot stripe also gives you a bit of scope for altering the waterline once you have launched the boat if you need to.
With most boats I try to completely finish the bottom, then turn them and work on the topsides right way up so you only need to turn it once, reducing the risk of potential marking to the finish. In wood boats where I am glassing the bottom, I finish the glass 5-10mm below the finished waterline, then take the fairing compound/primer and topcoat up to the actual waterline. This reduces the risk of glass fibres breaking through when you are working in this transition area and allows a bit of feathering to the thickness given by the glass as well.
Here are a couple of examples of boot stripes:
Hope that helps
Uploaded files:
Hi Dan,
Thanks for your quick feedback and recommendations.
Immediately after I posted my request another idea came to mind.
My situation is very similar to your first picture. There is a sharp edge between hull side and bottom along the chine. (The model for my boat is the Boesch 620 Acapulco based on the modified plans for the Glen-L Rivera).
The idea that came to my mind is to proceed as follows:
1. glassing the bottom up to the waterline (or an inch below as you recommended).
2. 3 coats of epoxy bottom and hull side
3. applying underwater paint just on the bottom up to the chine line
4. mark the waterline with a thin line only on the hull side and turn the boat upright
5. then varnishing the complete sides and deck (from deck down to the chine)
6. finally, the underwater paint on the ship’s side from the waterline down to the chine line
That would lead to have the same thickness of the varnish film on the entire hull side.
The edge would be exactly the chine line, except a tiny area at the bow.
It is questionable whether applying the underwater paint to the varnish will have a negative effect.
Yes you could do that, because you are using two part products, I wouldn't recommend putting single part varnish below the waterline.
Does your waterline drop below the chine line fwd? In my boat there is a small amount of bottom planking that shows up at the bow. This might affect your ability to finish at the chine line? Also if you intend to blend the two paint finishes on the chine line you will need to somehow finish them into one another without a line showing. You can do this with a bit of polishing on an external corner quite easily but I don't think it is as easy to conceal as under a boot stripe.