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Blood alcohol calculator for boaters
How much alcohol is in my blood after the sundowner, and can I still take the helm? This calculator for boaters estimates your blood alcohol from your body, your drinks and the time, then compares it with the limit where you sail. It deliberately shows a range, because every body breaks alcohol down differently. Your entries stay in your browser.
Work out your blood alcohol
This calculator only gives a rough guide and says nothing about whether you are fit to skipper. It is no substitute for a breath test or legal advice. The safest skipper is a sober one.
Alcohol limits on the water
In Germany the limit for whoever is in charge of a vessel on inland and maritime waterways is 0.5 per mille blood alcohol or 0.25 mg/l breath alcohol. Austria uses the same figures, while Spain's law states none. Sweden and Poland are stricter at 0.2 per mille.[1][2][3][4]
Worldwide the range runs from zero in the Czech Republic, Hungary and Bulgaria to 1.0 per mille in Finland. The USA and Canada set 0.8, the Australian states 0.5. The United Kingdom, Ireland and Portugal set no figure at all for leisure skippers; there it only matters whether you are impaired.[5][6][7]
| Sailing area | Blood alcohol limit |
|---|---|
| Europe | |
| Germany[1][2][13][1][13][14] | 0.5 ‰ |
| Austria[3][3] | 0.5 ‰ |
| Spain[4][15] | 0.5 ‰ |
| Belgium[16] | 0.5 ‰ |
| Bulgaria[17] | 0.0 ‰ |
| Boating in Croatia[18] | 0.5 ‰ |
| Cyprus[19] | 0.9 ‰ |
| Czech Republic[5] | 0.0 ‰ |
| Boating in Denmark[20] | 0.5 ‰ |
| Estonia[21] | 0.5 ‰ |
| Finland[6] | 1.0 ‰ |
| Boating in France[22] | no figure |
| Hungary[23] | 0.0 ‰ |
| Ireland[24] | no figure |
| Boating in Italy[25] | 0.5 ‰ |
| Latvia[26] | 0.5 ‰ |
| Luxembourg[27] | 0.5 ‰ |
| Boating in Malta[28] | 0.5 ‰ |
| Monaco[29] | no figure |
| Boating in Montenegro[30] | 0.5 ‰ |
| Boating in Netherlands[31] | 0.5 ‰ |
| Boating in Norway[32] | 0.8 ‰ |
| Boating in Poland[33][34] | 0.2 ‰ |
| Boating in Portugal[35] | no figure |
| Boating in Slovenia[36] | 0.5 ‰ |
| Boating in Sweden[37] | 0.2 ‰ |
| Boating in Switzerland[38] | 0.5 ‰ |
| Boating in Turkey[39] | 0.5 ‰ |
| United Kingdom[7] | no figure |
| Americas and Caribbean | |
| Argentina[40] | 0.5 ‰ |
| Canada[41] | 0.8 ‰ |
| U.S. Virgin Islands[42] | 0.8 ‰ |
| Boating in USA[43] | 0.8 ‰ |
| Asia and Oceania | |
| Australia: New South Wales[44] | 0.5 ‰ |
| Australia: Queensland[45] | 0.5 ‰ |
| Australia: South Australia[46] | 0.5 ‰ |
| Australia: Tasmania[47] | 0.5 ‰ |
| Australia: Victoria[48] | 0.5 ‰ |
| Australia: Western Australia[49] | 0.5 ‰ |
| Japan[50] | no figure |
| Philippines[51] | no figure |
| Africa | |
| Mauritius[52] | 0.5 ‰ |
| South Africa[53] | 0.5 ‰ |
How the calculator estimates
Alcohol spreads through the water in your body. The calculator estimates how much water that is with the Watson formula, from sex, age, height and weight. With more body fat at the same weight, you reach higher values.[8]
Volume and strength give the pure alcohol: half a litre of 5 % beer holds 20 g. Part of it never reaches the blood, the absorption deficit of 10 to 30 %. The body then breaks down roughly 0.1 to 0.2 per mille an hour. As both vary, the calculator shows a range rather than a single figure.[9]
No formula accounts for food, drinking pace, medication, fatigue, heat or sea state. Shortly after the last drink the level can still rise.
Alcohol and boat insurance
For gross negligence the hull cover may reduce its payment in line with the degree of fault. Basis Plus waives this up to 25 % of the sum insured, Premium up to 50 %. The waiver does not apply when the loss is due to alcohol or drugs. Clause A-7 in Premium (German)[10][11]
The water sports accident cover excludes accidents caused by impaired consciousness, expressly including alcohol as the cause. This applies at all three levels. Clause A-4.1 (German)[12]
Fines and criminal law in Germany
From 0.5 per mille the official German catalogue sets 750 to 2,500 € at sea and 350 to 2,500 € inland. Unlike road traffic it has no separate level from 1.1 per mille. Boating fines in Germany[13]
Anyone who steers a vessel when alcohol means they can no longer do so safely commits a criminal offence under section 315a of the German Criminal Code, even if nothing happens. No law fixes the level at which this applies without visible symptoms.[14]
Frequently asked questions
How much alcohol is allowed when boating?
On German inland and maritime waterways the skipper's limit is 0.5 per mille or 0.25 mg/l breath alcohol, and the same in Austria. Anyone visibly impaired can be penalised below that.
How accurate is the calculator?
It estimates a range using recognised formulas. Your real level depends on food, drinking pace, health and how you feel that day, and may fall outside the range. Being just under the limit is therefore no safe answer.
How long does it take for alcohol to wear off?
The body breaks down about 0.1 to 0.2 per mille an hour. Getting from 0.5 per mille to zero can take up to five hours, and after a long evening there may still be alcohol in your blood the next morning.
Does boat insurance pay if alcohol was involved?
The hull cover may reduce payment for gross negligence. The waiver of that reduction in Basis Plus and Premium does not apply when the loss is due to alcohol. The water sports accident cover excludes accidents caused by alcohol-related impairment of consciousness.
What is the limit for boaters in other countries?
Usually 0.5 per mille, as in Croatia, Italy, the Netherlands, Denmark, Turkey and Australia. Sweden and Poland allow 0.2, the Czech Republic and Hungary zero. The USA and Canada set 0.8, Finland 1.0. The United Kingdom, Ireland and Portugal set no figure for leisure skippers.
Does the limit also apply to jet skis, kites and windsurfers?
On German maritime waterways, yes: the regulations expressly extend the limit to jet skis as well as kite and windsurf boards.
More for your time on the water
Boat insurance Alcohol on board Boating fines in Germany Boating abroad Boat papers checklist Lifejacket finder
Sources
Legal position as of 8 November 2026, all sources retrieved that day.
- Seeschifffahrtsstraßen-Ordnung (SeeSchStrO) § 3
- Binnenschifffahrtsstraßen-Einführungsverordnung § 6 mit BinSchStrO § 1.03
- Schifffahrtsgesetz (SchFG) §§ 6, 42 und 125, Österreich
- Real Decreto Legislativo 2/2011 (TRLPEMM), art. 307 y 308
- Zákon 114/1995 Sb. o vnitrozemské plavbě, § 43 odst. 2 písm. p)
- Rikoslaki 39/1889, Kapitel 23 § 5
- Railways and Transport Safety Act 2003, s. 80 und 81; SI 2004/827 art. 3
- Watson, Watson, Batt: Total body water volumes for adult males and females estimated from simple anthropometric measurements. American Journal of Clinical Nutrition 33 (1980), S. 27–39
- Wikipedia: Blutalkoholkonzentration (Widmark-Formel, Resorptionsdefizit, Abbauwert, mit Einzelnachweisen)
- AVB Wassersport-Kasko Basis Plus (5-2025nam), A-7
- AVB Wassersport-Kasko Premium (1-2025nam), A-7
- AVB Wassersport-Unfall Basis (1-2025nam), A-4.1.1; ebenso Basis Plus und Premium
- Buß- und Verwarnungsgeldkatalog Binnen- und Seeschifffahrtsstraßen (BVKatBin-See), WSV, Stand 01.06.2023
- Strafgesetzbuch (StGB) § 315a
- ADAC Skipper-Portal: Revier Spanien
- Belgisch Scheepvaartwetboek (Gesetz vom 08.05.2019), Art. 4.1.2.8/3
- Наредба за плаването и граничния режим (ПМС № 293/2009), чл. 7 т. 2
- Narodne novine 61/2011: Änderung des kroatischen Seegesetzbuchs (Pomorski zakonik), Art. 134
- Ο περί Ταχύπλοων Σκαφών Νόμος 56(I)/1992, Art. 7 und 8
- Danish Maritime Authority: FAQ on sailing under the influence of alcohol
- Meresõiduohutuse seadus, § 45 Abs. 4 und 4¹
- Code des transports, Art. L5531-20 und L5531-21
- 2012. évi II. törvény, 217. § a)
- Maritime Safety Act 2005, section 28(1)
- Codice della nautica da diporto (D.Lgs. 171/2005) Art. 53-bis, Gesetzestext bei brocardi.it
- Noteikumi par kuģošanas līdzekļu satiksmi iekšējos ūdeņos, Punkt 21.12.1
- Règlement de police pour la navigation de la Moselle, Art. 1.03 Nr. 4
- ADAC Skipper-Portal: Revier Malta
- Code de la mer, Art. L. 633-31
- Montenegro: Änderung des Seesicherheitsgesetzes (Zakon o sigurnosti pomorske plovidbe), FAOLEX
- Rijksoverheid: Regels voor alcoholgebruik op het water
- Lovdata: Lov om fritids- og småbåter (småbåtloven)
- Dziennik Ustaw 2025 poz. 734: Kodeks wykroczeń (Ordnungswidrigkeitengesetz), tekst jednolity
- Dziennik Ustaw 2023 poz. 2151: Ustawa o wychowaniu w trzeźwości i przeciwdziałaniu alkoholizmowi
- Código Penal, Art. 289
- Pomorski zakonik (PZ), Art. 63 und 987.a (PISRS)
- Riksdagen: Sjölag (1994:1009), 20. Kapitel
- Fedlex: Binnenschifffahrtsverordnung (BSV), SR 747.201.1
- Resmî Gazete 33140: Verordnung über private Boote und ihre Führer (2026)
- Prefectura Naval Argentina, Disposición 9/2011, Art. 1
- Criminal Code, § 320.14(1)(b) und § 320.11
- 33 CFR § 95.005 und § 95.020
- eCFR: 33 CFR Part 95, Operating a vessel while under the influence of alcohol
- Transport for NSW: Alcohol limits when driving a boat
- Queensland Government: Boating safety
- Harbors and Navigation Act 1993 (SA), s 70(2)
- Marine Safety (Misuse of Alcohol) Act 2006 (Tas), s 13 und 16
- Safe Transport Victoria, Recreational Boating Handbook: Alcohol and drugs
- Department of Transport WA: Marine alcohol and drug laws
- Gesetz über Schiffsoffiziere und Kleinbootführer, Art. 23-36 (Auszug MLIT)
- MARINA Memorandum Circular No. SC-2023-02
- Tourism Authority Act 2006, s 95
- SAMSA: National Small Vessel Safety Regulations 2007, Reg. 17
