Guide
How Strong Must a Mooring Cleat Be Under ISO 15084, and What Goes on the Drawing?
ISO 15084 is the small-craft standard for strong points that attach chains, cables and lines for anchoring, mooring and towing, applicable to craft with a hull length up to 24 m. Its strength requirement applies to the strong point as installed on the boat, so a cleat drawing cannot claim compliance by itself: the maker controls material, section and fastener holes, and the boat builder supplies the design load and proves the installation.
By Saola Manufacturing engineering team · Published · Updated
General information, not legal advice. This guide is for engineers at cleat, chock and bollard makers and for boatbuilders who need to pass a load requirement to a machining partner. It describes what the public pages for the standard and the European directive say, states plainly that the strength formula and test values are in the purchased text and are not given here, and sets out the drawing wording that keeps the division of responsibility clear. Numbers for cleat strength that circulate on retail and inspection-service websites were not verified against the standard and are not used.
On this page
What does ISO 15084 actually cover?
It specifies requirements for strong points for attaching chains, cables and lines used in anchoring, mooring and towing, for small craft up to 24 m hull length. It does not set anchor weights or chain and line lengths, and it excludes the strong point from which the craft tows other vessels.
The Estonian standards body lists EVS-EN ISO 15084:2018, titled “Small craft - Anchoring, mooring and towing - Strong points”, as valid from 16 October 2018 and replacing the 2003 edition (EVS record, 2018). BSI lists the same 2018 edition, published on 31 October 2018, with the scope wording above and the status “current, under review” (BSI Knowledge, 2018). Reviewed standards can change; ask the customer which edition governs the boat.
Neither public page names cleats or bollards in the scope text. The scope speaks of strong points, so which hardware counts as the strong point on a particular boat is defined by the boat builder under the standard’s own wording. A cleat maker should ask for that definition before putting any compliance wording on a drawing.
In engineering terms a cleat is the visible end of a load path: line, cleat, fasteners, backing and the hull structure. The standard’s requirement is for what the load path carries, not for one catalog part. That reading is the reason the rest of this guide separates the maker’s scope from the builder’s.
How strong must the cleat be?
The public pages for the standard give no load figure, so this guide gives none. The required load comes from the purchased standard and depends on the boat, and the boat builder passes the design load to the part maker.
Search results and retail pages quote minimum loads and formulas for cleats under this standard. This guide did not verify any of them against the licensed text, and a formula copied from a secondary page is exactly the kind of number that ends up wrong on a drawing. A cleat maker should not print a load requirement or a “rated” load without a source it can name and an edition it has read.
For the RFQ the cleaner route is to ask for the design load in writing: “Design load for this strong point: [value and unit] per [boat builder document], derived under ISO 15084 edition [year] by [boat builder].” The maker then designs the section and the fastener pattern to carry that number and shows the basis, whether that is calculation, test or comparison with a proven design, and the boat builder owns the compliance argument for the strong point.
This is also how the European directive frames it. The Commission’s application guide, section 3.9, says all watercraft, taking into account their design category and characteristics, must be fitted with one or more strong points or other means capable of safely accepting anchoring, mooring and towing loads, and lists EN ISO 15084 as the relevant harmonized standard (European Commission, RCD Application Guide, 2018). The obligation sits with the craft.
Who controls what: the cleat maker or the boat builder?
The cleat maker controls the part: alloy, section, hole pattern, edge finish and the certificate. The boat builder controls the strong point: fasteners, backing, hull structure, the design load and any installed test.
The table separates the two so that a drawing can reference it. The most common failure is an RFQ that sends only the cleat drawing and a one-line load requirement, which leaves the maker to guess whether the load is a design load, a proof load or a breaking load, and whether the cleat is tested alone or on a mock-up of the boat.
Where the division is unclear, write it into the PO: “Part maker supplies the cleat to this drawing. Compliance of the installed strong point is the boat builder’s.” That sentence does not weaken the part; it prevents a later dispute over who attested to what.
| Item | Cleat, chock or bollard maker | Boat builder (strong point) |
|---|---|---|
| Compliance claim | None on the part drawing | Claim for the installed strong point under the standard |
| Design load | Receives it in writing with its basis and edition | Derives it from the purchased standard for the boat |
| Material and section | Alloy, section and finish on the drawing, with a certificate | Accepts or sets the alloy; checks the section against the design load |
| Fastener holes | Hole pattern, diameter and countersink as drawn | Chooses fasteners, washers and torque |
| Backing plate and hull structure | Out of scope for the part | In scope for the strong point |
| Installed test | Not performed by the maker | Performed on the boat or a mock-up by the builder |
What belongs on a cleat or bollard drawing?
The alloy and condition, the section dimensions that matter to strength, the hole pattern with its tolerance, edge radii where the line bears, the finish, the certificate type, and a note that the design load comes from the boat builder.
Start with the material line. A workable note names the alloy by UNS number or standard, the product form (bar or casting), and the certificate type, as in the 3.1 vs 2.2 certificate guide. If the cleat is cast, add the casting specification and an acceptance rule for porosity in the base, since a flaw in a high-load area matters more than one in a cosmetic horn; the casting vs machining drawing guide covers how to show both states.
Then the features that govern the load path: base thickness, the fillet where the horn meets the base, the fastener hole pattern and the bearing face under the fastener head. Mark them as critical in the way the critical characteristics guide describes. Add an edge break where the line bears; the break sharp edges note gives the wording. Do not print a load, a safety factor or a standard clause on the part unless the boat builder supplied it.
Last, the note that makes the division explicit: “Design load and compliance of the installed strong point are by others per the customer’s documentation.” If a mock-up test is expected, say who builds the mock-up and who pays for the test.
Which materials do cleats use, and what does the maker verify?
Marine cleats are made in bronze, brass-based bronzes, aluminum and stainless. The maker verifies material identity, dimensions and finish; strength is the builder’s argument.
Gerr’s 2009 marine metals article notes that manganese bronze, Tobin bronze and commercial bronze are widely used for fittings like cleats and chocks because they are strong, easy to cast and easy to machine, but they are really brasses and are potential problems below the waterline; he also says aluminum is widely used for cleats and is weaker and softer than stainless, bronze or Monel (Gerr, High Strength with High Corrosion Resistance, 2009). The comparison guide on silicon bronze vs 316 for marine hardware covers how to choose.
For stainless cleats, BSSA says that 316 is susceptible to crevice and pitting corrosion in seawater and that crevices must be avoided (BSSA, 2026). A cleat base on a wet deck with a gasket or sealant line is a crevice you can design around, for example with a continuous sealant bead and a drain path.
Verification the maker can offer is dimensional and documentary: a measured report on the hole pattern and base thickness, the material certificate, positive material identification if the customer asks (see the PMI guide), and visual inspection of the finish. A pull test is the boat builder’s installed test unless the customer defines a part-level test and pays for the fixture.
Machining a cleat from bar or finishing a cast blank runs on CNC milling, with CNC turning for round bollard parts and inserts. Casting is placed with a partner foundry that Saola manages and does not name, and the quote names both production sites.
Frequently asked
What load does ISO 15084 require for a cleat?
The public EVS and BSI pages give no load figure. The value is in the purchased standard and depends on the boat, so ask the boat builder for the design load and its source.
Can I print "meets ISO 15084" on a cleat drawing?
Not on the part alone. The standard addresses strong points on small craft up to 24 m hull length, so compliance is claimed for the installed strong point by the boat builder.
Does ISO 15084 cover towing?
It covers strong points for anchoring, mooring and towing, but excludes the strong point from which the craft tows other vessels.
Is ISO 15084 a harmonized standard?
The European Commission’s 2018 application guide lists EN ISO 15084 as the harmonized standard for the anchoring, mooring and towing requirement; confirm against the current Official Journal list.
Who tests the cleat?
Typically the boat builder, on the installed strong point. A part-level test is possible if the customer defines the fixture, load and records and pays for it.
Sources
- EVS-EN ISO 15084:2018, Small craft - Anchoring, mooring and towing - Strong points, EVS, the Estonian standards body, valid from 16 October 2018
- BS EN ISO 15084:2018, Small craft - Anchoring, mooring and towing - Strong points, summary, BSI Knowledge, published 31 October 2018
- Recreational Craft Directive 2013/53/EU, Application Guide, section 3.9, European Commission, 2018 edition
- High Strength with High Corrosion Resistance (marine metals, part 2), Dave Gerr, Gerr Marine, 2009
- Selection of 316, 304 and 303 types of stainless steels for seawater applications, British Stainless Steel Association, accessed October 2026 (page copyright 2026)