"I made the product I wish I'd had 30 years ago. Takes some work but it works." — Lee
I've been detailing boats for over thirty years — most recently out here on Lake Chelan. Most of what I know got worked out on other people's hulls — what holds up, what doesn't, what the big-brand products quietly fail at when the conditions get specific.
T'sillan BDG is the wax I wish I'd had for the last thirty years.
— Lee · Local boydidgood
You've watched the white gelcoat under your covered slip go gray and speckled. You've spent weekends scrubbing droppings that wouldn't come off, and noticed the etched shadows they left behind. You've tried the peppermint sprays — they lasted about two weeks.
The damage isn't dirt. Spider droppings carry the same digestive enzymes spiders use to liquefy their prey — and on gelcoat, those enzymes etch. By the time you can see the stain, the gelcoat is already pitted underneath. No amount of scrubbing rebuilds the surface.
T'sillan BDG is a gelcoat-only bonding lotion designed to be massaged into a properly prepped surface — new, or freshly polished and free of oxidation. The oils absorb into the pores; what you buff off is the bonding layer that stays behind.
It will not restore oxidized gelcoat. It will not make a tired hull look new. Prep is the work; this is the protection that follows.
T'sillan BDG was engineered to do two things at once. For boats where spiders are the actual problem, it's a long-term presence that arachnid nervous systems read as hostile. For boats where the goal is simply keeping the gelcoat protected, it's a bonded coating that saturates the pores and seals the surface — wash-resistant, longer-lasting than any wax.
Spiders taste with their feet. The chemoreceptors that do the work sit on the tips of their legs — the tarsi — and every step is a chemical reading of what's underfoot. T'sillan BDG carries a proprietary blend of plant-derived monoterpenes that arachnid nervous systems read as hostile. When the chemoreceptors on a spider's tarsi meet a treated panel, the surface returns the wrong answer, and the spider moves on. Mammals don't have the receptor.
Peppermint and citrus sprays work on the same family of monoterpenes — but they sit on the surface, and the first hard rain takes them off. The active chemistry here is bonded into a polysiloxane carrier that seats into the gelcoat itself, so a wash-down doesn't lift it off. Same active mechanism. Different durability altogether.
After the bonded layer buffs out, what's left covers the smooth surface and sits down inside the pores. From there the oils release slowly over time — they're not trapped, they meter out. A spray sits on the surface and rinses off. This stays put because it's part of the gelcoat now, and the slow release is what makes it last seasons, not weeks.
We didn't invent the chemistry. We just made it stick.
Buffed and set. Safe to touch — pets and people. Still hostile to arachnids.
Concentrated terpene complex. Keep away from pets, eyes, and mucous membranes during application.
Polysiloxane carriers · proprietary bio-active terpene complex · hydrophobic polymers
Wash with Dawn, alcohol, or white vinegar & water — or a dedicated surface-prep wipe. Goal: a uniform gloss that throws a clean reflection at any angle. A flat panel should look mirror-ish. (Reflection at 45° is the rank-amateur threshold; aim higher.)
Tape off rubber, vinyl, canvas, seadecking, black trim, and any oxidized metal. Dried-on product is hard to remove from these surfaces.
Soft, clean foam applicator on a random orbital or DA polisher — speed set very low. Treat it like lotion, not wax. The orbital pattern fills round pores better than back-and-forth. Spread with the applicator — don't drip product onto the boat and smear it around.
The applicator should be soft enough that if you wiped it near a baby's face, the baby wouldn't care or make any sort of indication that it was abrasive. — Lee
Imagine pushing the product into the pores of a sponge. Work it until the product is barely visible on the surface. Longer working time = better result; the oils need time to absorb.
Clean microfiber or a fresh foam pad. What you're removing is the bonding layer — once buffed, the chemistry has already begun setting. No cure time required.
You'll notice fewer fingerprints than a traditional wax. The surface should feel set, not slick. If a panel looks uneven, hit it again — there's no penalty for a second pass.
Came from a video? Here's what T'sillan BDG actually is→
Start with the DeWalt. Fit the Quick Connect, mount a wool pad for the cutting passes and a foam pad to follow, then find what your gelcoat actually needs. Work from the most aggressive compound down — Super-Duty on heavy oxidation, Heavy Cut to even things out, Perfect-It EX AC to bring up the gloss. Test a panel before you commit; most boats don't need the heaviest cut.
Sealing is a different job. A dual-action polisher is a different animal from a rotary — random orbit, lighter touch, low speed — so don't reach for the DeWalt here. (No machine? A folded terrycloth towel applies it by hand.) Mount a soft black polishing pad, then choose the finish: a wax for those who want one, or T'sillan BDG for everyone else.
Wash regularly with mild, gelcoat-safe soaps — anything that won't strip wax. Soaps that add a film of protection are even better. Salt-a-way is a worthy additive even in freshwater. A few of the Turtle Wax car soaps leave a protective layer behind too.
The thing that kills any protective coating is dirt baked in by the sun. Don't let it sit. Rinse, wash, and the bond does the rest.
"That's part of the magic of maintaining a boat — fixing things before they are a problem." — Lee
"Gelcoat as a material is constantly curing. Like glass in old cathedrals, it's still considered a semi-solid liquid. As it ages, the pores expand constantly — meaning no matter how well insulated from the sun gelcoat could be, it will always begin to fade out due to its own nature. The struggle is legitimately real. I made this to give you a little bit of leverage in that battle. But it does take work."
T'sillan BDG is sold direct by Local boydidgood via PayPal. Your shipping address is collected at checkout — and there's a field below for the gelcoat color you're treating, in case there's anything worth flagging for your particular boat.
"Waste as much as you like — we have more." — Lee
A quick version and a full one. § 04 The Method above is the quick take — six numbered steps to follow at the boat. The "Full application instructions" accordion right under it is the complete walkthrough in Lee's voice, with the detail the six steps leave out. That full version is also a downloadable PDF — same thing, but you can print it or take it offline. Pick whichever fits how you read.
Lee also ships a business card with every bottle (call him if you'd rather talk it through), and there are over 400 videos on his channel demonstrating the underlying detailing work.
Discourages — doesn't kill. The chemistry tells the spider "don't stay," and the spider moves on. Spiders are beneficial in most boating environments (they eat the bugs that bite you), so the goal is to keep them off the surfaces that matter, not eliminate them from your slip.
Probably, though I haven't formally tested either. The chemistry that signals "not here" to a spider should read similarly to most small insects. T'sillan BDG was built for the spider problem first — treat any other coverage as a happy side effect.
The same family of monoterpenes does the active work — that part is shared chemistry. The difference is that sprays sit on the surface and wash off in the first rain (about two weeks of effective protection, per most users). T'sillan BDG bonds into the gelcoat itself and lasts 3–4 months per coat. You're paying for durability, not for a different active.
That's specifically what it was built for. Covered slips and boathouses are where spider pressure is highest and where the etching damage shows up worst on white gelcoat.
The active chemistry is plant-derived monoterpenes — the same compound class found in peppermint, citrus, and pine oils. Once bonded and buffed, the coating is set on the gelcoat rather than free in the water. The pre-application liquid should be handled like any concentrated essential oil — keep it out of the water during application.
Yes. The application method is standard for any bonded coating — prep, polish, mask, apply, buff. Any detailer who works with sealants will recognize the workflow. The toolkit above is what Lee uses; equivalent equipment is fine.