A boat’s maintenance history: which proofs really count

“Regularly maintained, invoices available.” Every listing says it. What counts for a buyer — or for a surveyor, an insurer, a court — is what is verifiable: a date, a document, a third party. This guide ranks maintenance proofs from the weakest to the strongest, says what each one is worth and not worth, and explains how to turn a box of invoices into a readable history.

The three levels of proof

Declared

The owner says they did, or had done, a piece of work on a date. This is the level of a paper logbook, a spreadsheet or a listing. It is not worthless: a log kept regularly for ten years, with the engine hours on every line, tells a coherent story that a buyer can cross-check. But it proves nothing: anyone can write a line dated three years ago last night.

Documented

A document backs up the declaration: a boatyard invoice, a till receipt for parts, a photo taken on the day of the work. The proof is worth what the document is worth:

• A professional’s invoice identifies the business (name, SIRET — the French business identification number), the date, sometimes the boat, and the details of the work. It is the best document. It remains fallible: an invoice may relate to a quote that was never carried out, or concern another boat.
• A receipt for parts (anodes, filters, oil, antifouling) proves a purchase on a date, not the fitting. Linked to a line in the log and an hours reading, it becomes credible.
• A photo proves a condition at a moment, if its date is that of the shot (the camera’s metadata) and not that of the file. A photo of the hull after a haul-out, of the open engine, of the new impeller, is worth more than a long paragraph.

Confirmed by the professional

The boatyard or the mechanic who did the work confirms, themselves, that they did it. This is the strongest level: an identified third party stakes their reputation on a specific job. In practice, few boat owners dare to ask their boatyard for a certificate; Hullteam does it for them, through a link sent to the professional — no account to create, three buttons: I confirm, it was not us, I dispute.

Two dates, always

A maintenance proof has two dates: that of the work (declared, on the invoice or from memory) and that of the entry in the log (recorded). In a paper logbook, the two merge, and that is the problem: nothing stops you filling in ten pages the day before the sale. A serious digital log keeps the date of entry, makes it tamper-proof, and marks the gap: a job from 2019 entered in 2026 is a job “entered retroactively”. That is not a flaw — rebuilding a history is normal —, it is information the buyer deserves.

What proves nothing

• A quote. It proves an intention, not a piece of work.
• An invoice without a date, without a business name, or from a business that does not exist in the register (Hullteam checks the issuer in the French business register and flags a business that has been struck off).
• A paper logbook filled in with a single handwriting, in the same ink, over ten years.
• The sentence “the boatyard has always looked after it”, without a single invoice.
• Engine hours that go down from one job to the next: at best a mistake, at worst a meter changed without saying so. A good log flags it without blocking it: a twenty-year-old boat has an irregular history.

Rebuilding a history from a box of invoices

This is the most common case: years of invoices in a folder, receipts in the glovebox, photos on three successive phones. Method:

• Take everything out and sort it by year. Throw nothing away, not even an illegible invoice: it will at least prove a date.
• For each boatyard invoice, identify the separate pieces of work it contains. A winter storage invoice often hides three jobs: oil change, haul-out, anodes. Each piece of work becomes a line in the log, dated with the invoice.
• Attach the parts receipts to the line they concern, or create a “done by the owner” line for the maintenance you did yourself.
• Find the engine hours when they appear on the invoice (boatyards often note them) and copy them across.
• Add the dated photos you have: haul-out, engine, rigging, new sails.
• For major work (engine, rigging, structural repair), ask the professional to confirm.

Hullteam automates most of it: you upload the invoices in bulk (a photo on your phone or files), each one is read, the issuer is checked in the register, the lines are proposed with their date, amount and category, and you accept, correct or discard each proposal. A box of sixty invoices becomes a history of sixty documented lines in less than an hour.

Sealing, so that it holds

Once entered, a line must become impossible to change quietly. In the Hullteam log, each line is locked seven days after it is entered and takes a fingerprint that depends on the previous line; all the chains are timestamped every night by an independent service. Correcting a mistake is done with a new line, never by rewriting the old one. That is what lets you tell the buyer: here is the history as it was written, on the dates it was written.

To sell: the guide selling your used boat and the sale file. To buy: the checklist before you sign.