Hull Cleaning Diver Bookkeeping: Per-Foot Pricing, Route Contracts, and Marina Insurance

A fouled hull is not a cosmetic problem. Marine researchers and the International Maritime Organization put the fuel penalty from biofouling at up to 30 to 35 percent, and even a thin slime layer measurably increases drag. In warm water, a boat that sits for a month grows a beard — and its owner pays for that beard at every fill-up until someone scrapes it off. That someone is you, on a recurring schedule, at two to five dollars per foot, every two to four weeks, for as long as the boat stays in the water.

Hull cleaning is one of the rare service businesses where the customer needs you on a timetable set by biology rather than by choice. Barnacles do not negotiate. But the divers who make real money at it treat it as a route business with tight books, not as gig work with a wetsuit. This guide covers the pricing math, the recurring-contract engine, the insurance that gets you past the dock gate, and the tax basics that keep the money you earn.

How the Money Works: Per-Foot Pricing and the Minimum That Protects You​

Hull cleaning is priced by the foot of boat length, with the rate varying by region, boat type, and how often you dive it. Working divers and marina-area price sheets cluster in a familiar band:

• Recurring monthly customers: roughly $2.50 to $4 per foot per cleaning in most US coastal markets, with Florida and Gulf Coast routes often around $3 per foot.
• One-time or first-time cleans: $4 to $5-plus per foot, because a neglected bottom can take two to three times as long as a maintained one.
• Powerboats vs. sailboats: many divers charge powerboats more per foot — wider beams mean more surface area per foot of length.
• Zinc (sacrificial anode) replacement: almost always billed extra, typically $15 to $40-plus in labor per zinc plus the cost of the part.

The most important number on your price sheet is not the per-foot rate. It is the minimum. A 25-foot boat at $3 per foot is $75 — before drive time, gear prep, and the marina parking dance. Established operators set minimums of $75 to $150 per visit so small boats do not eat the day. Quote the minimum on every estimate, in writing, before you get wet.

Three pricing rules that separate profitable routes from charity swims:

1. Price the first clean separately. Never quote a recurring rate for a bottom you have not seen. Do a first clean at the one-time rate, then offer the monthly price once the hull is at baseline.
2. Charge for growth level, not just length. A boat that skipped two months in August water is a different job than the same boat on schedule. State in your service agreement that heavy-fouling visits bill at the one-time rate.
3. Raise rates on a schedule, not by apology. Fuel, zincs, and insurance rise every year. A short annual notice — "rates adjust 5 percent each January" — beats an awkward conversation after three years of frozen prices.

The Real Product: Recurring Monthly Route Contracts​

One-off cleans pay for the day. Routes pay for the year. A hull cleaner with 100 monthly boats at an average of $100 per visit runs a $10,000-a-month business before zincs, prop work, and referrals — and veteran operators report roughly that shape of route in busy Southwest Florida markets.

Recurrence works because warm-water boats need cleaning every two to four weeks and cold-water boats need it through the season. Your job is to convert that biological fact into signed routine:

• Sell the schedule, not the swim. Offer "monthly bottom maintenance" with automatic visits, not "call me when it looks fuzzy." The customer buys peace of mind; you buy predictable revenue.
• Build density before range. Five boats on one dock beats five boats across three marinas. Every minute driving is a minute unpaid, so discount strategically to fill out docks where you already work — a 10 percent dock-mate discount that saves you an hour of driving is a raise, not a cut.
• Handle prepaid packages as deferred revenue. If a customer prepays a quarter or a season, that cash is not all income on day one — you earn it one dive at a time. Record the prepayment as a liability and recognize revenue as you complete each visit. It keeps your monthly profit honest and tells you exactly what you still owe in dives if a customer asks for a refund mid-season.
• Plan for pauses. Haul-outs, hurricanes, and cruising seasons interrupt routes. Write your policy down: paused accounts resume at the current rate, and boats idle over 60 days restart at the first-clean rate.

Track two numbers every month: revenue per route-hour (total route revenue divided by all hours including drive and prep) and boats per day. If revenue per route-hour stalls while fuel and insurance climb, your pricing — not your effort — is the problem.

What Marinas Require Before You Touch a Hull​

Here is the gate most newcomers underestimate: you cannot simply walk down a dock with a scraper. Marinas and boatyards set the terms for who works on customer boats in their slips, and their requirements are non-negotiable.

• Marine general liability insurance is the baseline — typically $1 million in limits to match the marina's own policy. Standard handyman general liability is not the same thing; you need a marine-artisan policy whose class codes cover divers doing bottom cleaning, zinc replacement, and prop work.
• Workers' compensation is frequently required even if you work solo. Several states and many marinas insist on it regardless of headcount, and the combined premiums are a real budget line — solo operators commonly report total insurance costs in the thousands per year, which is why part-timing this trade is harder than it looks.
• A certificate of insurance naming the marina as additional insured. Each marina wants its own certificate on file before your first dive. Build a simple renewal calendar: certificates expire, dockmasters change, and "your insurance lapsed" is how you lose a whole dock of boats in one email.
• Local in-water cleaning rules. Some jurisdictions restrict scrubbing certain bottom paints in the water or require debris capture, and Clean Marina programs publish diver guidelines you are expected to follow. Check the rules in every harbor you work — a diver with proper insurance and a reputation for following the guidelines has no trouble getting dock access.

Bookkeeping treatment matters here: insurance is usually paid annually or quarterly but protects you monthly. Record the payment as prepaid insurance and amortize it across the covered months, so a $3,000 premium paid in January does not make January look catastrophic and the next eleven months look free. And keep every certificate, renewal notice, and marina vendor agreement in one folder — when a dockmaster asks for paperwork, "I will send it tonight" is the difference between keeping and losing the account.

Gear: What It Costs and How to Write It Off​

A working hull cleaner travels lighter than most trades, but the kit still adds up: hookah surface-supply rig or tanks, regulators, wetsuits or drysuit, scrapers and brushes, underwater lights, zinc inventory, a tender or skiff for mooring-field work, and the truck that hauls it all. A hookah setup alone can run from a few hundred dollars for a basic rig into the thousands for a pro-grade compressor system — and compressors need maintenance reserves, not just purchase budgets.

For the books, keep three buckets straight:

• Equipment you depreciate or expense. Dive gear, compressors, and electronics are business assets. Section 179 expensing generally lets a small operator deduct the full cost of qualifying equipment in the year it goes into service rather than depreciating it over several years — the limits are far above what a dive rig costs, but confirm the current IRS figures for your tax year before you file.
• Consumables you expense immediately. Brushes, scrapers, zincs you install, wetsuit repairs — these are supplies, deducted when used. Track zincs per job: part cost plus your markup, billed to the customer, so anode work shows its own margin instead of vanishing into "miscellaneous."
• The truck and the mileage. If your vehicle mixes personal and route driving, keep a mileage log and choose each year between the standard mileage rate and actual expenses. A route business lives in its truck; sloppy vehicle records are one of the most common deductions solo operators leave on the table — or lose in an audit.

Set up separate expense categories from day one: gear, consumables, fuel and vehicle, insurance, marina and launch fees, phone and scheduling software, and professional services. When every dollar lands in a labeled bucket the same week it is spent, your year-end tax return practically writes itself — and you can answer the only question that matters mid-year: which costs are rising faster than your rates?

The Taxes Nobody Warns New Divers About​

Most hull cleaners start as sole proprietors, which means the tax picture is simple but unforgiving. There is no employer withholding anything for you, so every obligation below lands on your calendar personally.

• Income and self-employment tax. Net profit flows to your personal return on Schedule C, and self-employment tax adds roughly 15.3 percent on top of income tax up to the annual Social Security wage base. A diver netting $60,000 owes on the order of $8,000-plus in self-employment tax alone — the single biggest surprise for people leaving W-2 jobs.
• Quarterly estimated payments. Because nothing is withheld, the IRS expects you to pay as you go in four installments. Miss them and you owe penalties on top of the tax. The practical habit: move 25 to 30 percent of every week's deposits into a separate tax savings account before you spend a dollar of it.
• 1099s from commercial clients. Marinas, yacht managers, and brokerages that pay you over the reporting threshold will send 1099s — and the IRS gets a copy. Reconcile every 1099 against your own records; a missing form does not make the income tax-free, and a wrong one needs correcting before April.
• Sales tax on services varies by state. Some states tax cleaning services, most do not — but the ones that do will happily assess you for every uncollected dollar going back years. Verify your state's treatment of in-water cleaning services before your first invoice, not after your first audit letter.
• Hiring a second diver changes everything. The moment you bring on help, you face the employee-versus-contractor classification, payroll filings, and workers' comp for real. A second diver on a busy route is often the highest-ROI hire in the business — just price the payroll burden into your rates before you post the job, not after.

Open a dedicated business bank account before your first paid dive, and run every business dollar through it. Commingling personal and business money in one account is the fastest way to turn a simple Schedule C into an expensive reconstruction project.

Mistakes That Sink New Hull Cleaners​

Watch for these five — each one shows up constantly in dock talk among divers who figured it out the hard way:

1. Diving without a minimum. Small boats at straight per-foot rates lose money once drive time counts. Set the minimum and hold it.
2. Quoting recurring rates sight unseen. The "just a light slime" boat is always worse than described. First clean at the one-time rate, every time.
3. Forgetting the drive. If your route math ignores windshield time, you will expand your territory straight into unprofitability. Density first, range second.
4. Skipping quarterly estimates. April's bill-plus-penalty is the classic first-year gut punch. Automate the weekly tax transfer and never touch it.
5. Treating insurance as optional until asked. The marina that finally demands your certificate does not care that you meant to get it. No certificate, no dock, no route — get covered before you market to marina boats.

Keep Your Books as Clean as Your Hulls​

A hull cleaning route is a simple business wearing a wetsuit: recurring revenue, per-job costs, and one big annual insurance bill. Track revenue per route-hour, recognize prepaid packages as you earn them, amortize insurance monthly, and move tax money aside weekly — and the books stay as clean as the bottoms. Beancount.io offers plain-text accounting that is transparent, version-controlled, and AI-ready, so your route revenue, zinc inventory, and gear depreciation live in one ledger you fully control. Get started for free and see why developers and finance professionals are switching to plain-text accounting.