Getting started
Three things at the start: check the shares, complete the boat, enter the season’s bookings. Everything else follows from that.
Each group has exactly one administrator — whoever keeps the logbook. They assign shares and finalise the accounts. Everything else is open to all co-owners: booking, recording expenses and putting decisions to the vote.
Top right you switch the language — eleven to choose from, and the choice is remembered. Every email goes out in its recipient’s language, not the sender’s.
Everything that touches money is traceable: every change to an amount is logged, with name and time. That is not mistrust — it is what a group must still be able to answer years later.
Members and shares
Shares are in per mille, not percent: that way thirds come out even. Together they should be 1000 ‰; that is not enforced, because a group still forming sometimes has 800. The difference is shown at the top, every time.
Leaving does not delete, it sets an end date. Only then do the accounts of the year someone was still a member stay correct — even years later, when someone asks.
The postal address is not a formality: an apportionment is invoiced, and an invoice without an address is not one. And when something happens at the dock, you need a phone number, not an email address.
The boat
The boat’s details live here: model, year, home port, registration, MMSI, call sign. They are the same ones the logbook holds — what is missing here is missing there too.
For the home port, enter the town only — no dock, no berth number. Only then does the pin sit correctly on the portal’s home-port map. Suggestions appear as you type.
The photo sits at the top with the details. If the logbook holds one, the sync fetches it; your own is never overwritten. The file lives outside the web directory and is reachable only through the signed-in page.
Calendar and bookings
What you book are nights, not days: the day of departure stays free so the next person can take over the same day. Drag across the grid and book — or use the form above for periods that cross a month.
Every member has their own colour, and the type is marked beside it: ⛵ trip, 🔧 maintenance, ⛔ blocked. At a glance you see who sails when — and what is not a trip at all.
Below the grid you see how many nights each person is entitled to by share, how many are used and what is left. That is information, not a barrier: nobody is stopped for going over — but everyone can see it.
Your bookings can go into your own calendar — Apple, Outlook, Google. “Subscribe” keeps itself up to date; a downloaded file does not. The address shows bookings only, no expenses and no postal addresses, and can be revoked at any time.
Public holidays can be switched on per country under Settings, in Germany also per state. Several countries are possible — a group does not always come from one. The point is not the holiday itself but the long weekend everyone argues about.
For some weeks — usually the holidays — the co-ownership can decide that there is no direct booking: the manager sets these allocation periods under Settings, per year. Whoever wants to sail then enters a request; the manager approves it individually or allocates the whole round at once. In the calendar such days are hatched, in the app they have a dashed border.
Recurring bookings are set up as a series: a period, an interval (“every second week”) and an end date. Dates that hit an existing booking or an allocation period are skipped — the feedback says how many were made and how many were not. Each date is then an ordinary booking and can be cancelled individually.
Expenses and receipts
Every item gets a receipt — photographed where it occurs. Then nobody has to gather them in spring, and when a question comes up the invoice sits on the line instead of in a folder.
Paid by decides who gets money back at year end. “Joint account” means: out of the common purse, nobody advanced anything.
The split applies per item: berth by share, diesel by nights, self-inflicted damage alone. If the key is missing (usage without recorded bookings, say), the item falls back to shares — and the accounts say so instead of letting it happen silently.
If a service runs across the year end — a policy from 1 April to 31 March — enter the service period. The amount is then split across both years to the day, so one year does not carry fifteen months of insurance while a later joiner carries none.
The cash account
The accounts say who owes whom what at year end. The cash account says whether there is money now — and in spring, when the berth falls due, that is the more pressing question.
The balance is calculated, not stored: opening balance + payments in − everything paid from the joint account. What someone advanced privately is not in the cash account but in the annual accounts.
Whoever keeps the cash account is named in the settings and may record payments in. Often that is not the same person who keeps the logbook — and that separation is what makes a joint account bearable. If nobody is named, the administrator keeps it.
Annual accounts
Three figures per person: Owed is the share of costs, Paid out is what that person advanced, Balance is the difference. Positive means money back, negative means paying in.
Costs are split by the state on the day of the item, not today’s: buying a share in September does not retroactively increase your part of January’s insurance.
Nothing is rounded away: remaining cents go to the largest remainders, so the total is exact. Over the years, nothing accumulates that no one can explain.
Finalising freezes the year: its items can no longer be changed, and the figures stay as agreed — even if someone leaves later. As long as an item cannot be allocated, nothing is finalised.
Decisions
A majority counts against everyone entitled to vote, not against the votes cast. Not voting therefore works like a vote against. That is the stricter reading, and the fairer one: otherwise a €60,000 decision could pass on a single yes while the others are on holiday.
The basis is either the share or the head — usually the share in a fractional community, the head in a partnership. The majority is simple, two thirds or unanimous. Both are set per decision, because not every decision needs the same threshold.
A topic can run in several stages: first the principle (“we buy a new genoa, about €2,000”), then the choice between quotes. The follow-up hangs on the topic but has its own majority and deadline — €2,000 is decided differently from which sailmaker.
In a choice between quotes, each vote goes to exactly one. The quote with the greatest weight is accepted, provided it reaches the threshold. If none does, nothing is decided — not “the best one wins”. A quote can only be added while nobody has voted.
Every decision needs someone to carry it out. A passed decision without a name is a statement of intent: “we buy the new genoa” sits in the minutes, and in May it is not there because everyone thought someone else would. A decision marked as an acquisition moves into the inventory once carried out.
Own work
Hours are recorded and shown — at first without a value in money. Everyone enters their own; the administrator may enter for others. Work entered by a third party would be a claim about someone else’s time.
They only turn into money with a voted hourly rate. There is deliberately no field for it in Settings: anyone who could set it there could retroactively redistribute other people’s money — which is exactly what the vote prevents.
The rate can be decided per person: four hours of electrics is not the same as four hours of sanding. A personal rate beats the general one. Each entry is valued with the rate that applied on the day the work was done — a later decision never changes what applied to past work.
Inventory
This is what the group owns: lifejackets, the second anchor, spare parts — no provisions. Each item carries an acquisition date and price; the age follows from that. Whoever leaves sells a share in a boat WITH its equipment.
What is on board and where it sits comes from Kielwasser and the app — that is where it is maintained, in the harbour, with the box in hand. What is added here (price, date, inspection) is unknown to the app and stays untouched.
An inspection date — liferaft, extinguisher, lifejackets — announces itself 60 days ahead at the top of the page. That is the reason to look here before casting off.
Documents
Insurance policy, berth contract, the agreement. The expiry date is the real reason for this page: it flags in good time what needs renewing. The files live outside the web directory and are reachable only through your login — not via a link that can be passed on.
Expired documents are not deleted; they move into the archive, sorted by year. A 2024 policy proves the boat was insured in 2024 — and that is exactly what someone asks years later.
Kielwasser and the app
Two names keep coming up here. kielwasser.blog is our portal for sailors; there every boat has its logbook — its own page with the ship’s details, crew and passages. Rubberduck is our phone app, the logbook on board. The two belong together: the app writes, the logbook keeps. What the app does is described here.
The logbook on kielwasser.blog is a requirement, not an accessory: boat, crew and bookings reach the app from there. Without it the web interface still works — the app stays empty.
In the sync, Kielwasser is the source and MitReeder mirrors it. Only gaps are filled — your own entries stay unless you explicitly say otherwise. Boat documents come along; crew papers do not — those belong to the person, not the boat.
After purchase, the logbook is marked as a MitReeder logbook. The app path hangs on that: owners and co-owners without a connected app get the invitation, and after connecting, the voucher for permanent use automatically. The mark can only be set from here — a logbook owner cannot grant it to themselves.
In the app you find the co-ownership under “More → MitReeder”: booking calendar, decisions, costs with a receipt from the camera, work hours and the documents. Whatever arrives by e-mail — a booking, a vote, an expiring insurance — also arrives as a notification on the phone and is kept there for 90 days under “Messages” to read again; tapping it takes you straight into the section. Crew does not see it.
Subscription, invoices, data
The subscription is per boat, not per head: €149 a year, any number of members. The owner pays for everyone. You manage invoices, payment methods and cancellation yourselves through the subscription portal under Settings.
Under Settings you can download an archive at any time: every table as CSV, plus receipts, documents and the boat photo. That is your data, not ours — and the reason a cancellation destroys nothing.
A second group is not created in here but through the regular route at /anlegen/: a group comes into being through payment, and a second path around that would be exactly the hole this order is meant to prevent.
Something missing here?
Write to ahoi@rubberduck-software.com. A question this page does not answer is a fault of the page — not of you.