Cutless marine bearings: shaft sizes, inch and metric charts, clearance and replacement
A marine Cutless or cutlass bearing supports a rotating propeller shaft in a strut, P-bracket or stern tube. In the Johnson Cutless design, water lubricates a grooved rubber lining bonded to a shell. Identify the shaft diameter, shell outside diameter and bearing length separately: a “1 inch cutlass bearing” is not one unique replacement part.
On this page16 sections ⌄
Cutless, cutlass, stern-tube and strut bearings: what the names mean
Water moves through the grooves and supports lubrication at the shaft/lining interface. A resilient water-lubricated sleeve is a different mechanism from a ball bearing. Lubrication, heat removal and flushing depend on the complete installation, not just on the material name.
On smaller screens, scroll the table sideways to read all columns.
| Term | Component or construction | Do not confuse it with |
|---|---|---|
| Johnson Cutless | Duramax trade name for the referenced water-lubricated bearing system | A generic approval for every brand called cutlass |
| Strut / P-bracket bearing | Shaft support in an external bracket | A rolling bearing inside an outdrive |
| Stern-tube bearing | Shaft support within the tube arrangement | The shaft seal or stuffing box |
| Naval-brass sleeve | Rubber lining bonded into a brass shell | An unlined solid bronze bushing |
| Non-metallic sleeve | The referenced Johnson family uses a reinforced thermoset shell | Every polymer or phenolic bearing having identical tolerances |
| Flanged / split flanged | A retained flange or split bearing construction | A sleeve selected only by shaft size |
Three dimensions to record before looking for a replacement
The table dimensions identify catalogue candidates; they are not measured running clearances or universal press-fit tolerances. Retain fractional-inch labels until the units are clear. One inch is exactly 25.4 mm: 1-1/4 in is 31.75 mm and 1-1/2 in is 38.1 mm.
On smaller screens, scroll the table sideways to read all columns.
| Measurement | Record | Common error |
|---|---|---|
| A: nominal shaft/journal diameter | The actual shaft or wear-sleeve diameter in the bearing | Treating a worn rubber opening as the catalogue shaft size |
| B: shell outside diameter | Bearing shell OD and the cleaned housing bore | Assuming every 1 in shaft uses a 1-1/4 in shell |
| C: overall bearing length | Original bearing and available housing length | Assuming all parts with the same shaft and OD are equally long |
| Additional fit details | Retainers, flange/pilot, material, water grooves, tolerances | Choosing from d×D×L without checking the assembly |
Johnson Cutless brass sleeve chart: 3/4 to 1-3/4 inch shafts
All 27 entries on catalogue page 4. A is nominal shaft diameter, B is shell OD and C is length, all in inches. Slimline is the catalogue designation. This is not a stock list or a claim that other brands interchange.
On smaller screens, scroll the table sideways to read all columns.
| Part number | Code | Shaft A in | Shell OD B in | Length C in |
|---|---|---|---|---|
| 870192100 | ABLE | 3/4 | 1 1/4 | 3 |
| 870222100 | ACID (slimline) | 7/8 | 1 1/4 | 3 1/2 |
| 870222101 | APEX | 7/8 | 1 3/8 | 3 1/2 |
| 870222102 | ATOM | 7/8 | 1 1/2 | 3 1/2 |
| 870252100 | BACK (slimline) | 1 | 1 1/4 | 4 |
| 870252144 | BADE (slimline) | 1 | 1 1/4 | 6 |
| 870252101 | BAIT | 1 | 1 3/8 | 4 |
| 870252102 | BALE | 1 | 1 1/2 | 4 |
| 870252103 | BAND | 1 | 1 5/8 | 4 |
| 870252104 | BASE | 1 | 2 | 4 |
| 870292100 | BEAM (slimline) | 1 1/8 | 1 1/2 | 4 1/2 |
| 870292101 | BELT | 1 1/8 | 1 5/8 | 4 1/2 |
| 870292102 | BEND | 1 1/8 | 1 3/4 | 4 1/2 |
| 870292103 | BILL | 1 1/8 | 2 | 4 1/2 |
| 870322100 | BIND (slimline) | 1 1/4 | 1 1/2 | 5 |
| 870322101 | BIRD | 1 1/4 | 1 3/4 | 5 |
| 870322102 | BITE | 1 1/4 | 2 | 5 |
| 870322103 | BLOW | 1 1/4 | 2 1/8 | 5 |
| 870352100 | BOAT | 1 3/8 | 1 7/8 | 5 1/2 |
| 870352101 | BOLD | 1 3/8 | 2 | 5 1/2 |
| 870352102 | BOND | 1 3/8 | 2 1/8 | 5 1/2 |
| 870352103 | BOOT | 1 3/8 | 2 3/8 | 5 1/2 |
| 870382100 | BOSS | 1 1/2 | 2 | 6 |
| 870382101 | BRAD | 1 1/2 | 2 3/8 | 6 |
| 870412100 | BREW | 1 5/8 | 2 1/8 | 6 1/2 |
| 870412101 | BRIM | 1 5/8 | 2 5/8 | 6 1/2 |
| 870452100 | BROW | 1 3/4 | 2 3/8 | 7 |
Johnson Cutless metric brass sleeve chart: 25 to 140 mm shafts
All 25 entries on catalogue page 6. Dimensions are the stated millimetre values, not rounded conversions from an inch-series part.
On smaller screens, scroll the table sideways to read all columns.
| Part number | Shaft A mm | Shell OD B mm | Length C mm |
|---|---|---|---|
| 870254100 | 25 | 40 | 100 |
| 870284100 | 28 | 42 | 112 |
| 870304100 | 30 | 45 | 120 |
| 870324100 | 32 | 45 | 128 |
| 870354100 | 35 | 50 | 140 |
| 870384100 | 38 | 55 | 152 |
| 870404100 | 40 | 55 | 160 |
| 870454100 | 45 | 65 | 180 |
| 870504100 | 50 | 70 | 200 |
| 870554100 | 55 | 75 | 220 |
| 870604100 | 60 | 80 | 240 |
| 870654100 | 65 | 85 | 260 |
| 870704100 | 70 | 90 | 280 |
| 870754100 | 75 | 95 | 300 |
| 870804100 | 80 | 100 | 320 |
| 870854100 | 85 | 105 | 340 |
| 870904100 | 90 | 110 | 360 |
| 870954100 | 95 | 115 | 380 |
| 871004100 | 100 | 125 | 400 |
| 871054100 | 105 | 130 | 420 |
| 871104100 | 110 | 135 | 440 |
| 871154100 | 115 | 145 | 460 |
| 871204100 | 120 | 155 | 480 |
| 871304100 | 130 | 170 | 520 |
| 871404100 | 140 | 180 | 560 |
Why a 1 inch, 1.25 inch or 1.5 inch description is incomplete
On smaller screens, scroll the table sideways to read all columns.
| Requested shaft | Catalogue examples | What changes |
|---|---|---|
| 1 in | BACK 870252100: 1×1-1/4×4 in; BADE 870252144: 1×1-1/4×6 in | Same shaft and OD; different lengths |
| 1 in | BAIT: 1×1-3/8×4 in; BALE: 1×1-1/2×4 in | Same shaft and length; different shell ODs |
| 1-1/4 in / 1.25 in | BIND: 1-1/4×1-1/2×5 in; BIRD: 1-1/4×1-3/4×5 in | Housing bore and shell construction must match |
| 1-1/2 in / 1.5 in | BOSS: 1-1/2×2×6 in; BRAD: 1-1/2×2-3/8×6 in | Different housing diameters |
| 25 mm | 870254100: 25×40×100 mm | Not a 1 in shaft bearing |
Does a Catalina, Beneteau, Jeanneau or MasterCraft name identify the bearing?
No. Model, build, shaft size and previous modifications can differ. Record the installed dimensions and original part reference; the examples here are not model-specific vessel fitment.
Can I replace a Vetus or Morse part with one of these codes?
Only after the exact manufacturer specification and assembly are verified. A Johnson catalogue row supplies a dimensional candidate, not an official cross-brand replacement.
Running clearance: measurement method and the catalogue footnote
The catalogue’s page-19 clearance table includes a footnote that Duramax adjusted over-shaft clearances for positive stainless-steel shaft tolerances. Therefore, the historical table is not presented here as a current universal acceptance or machining limit. Obtain the clearance for the exact bearing, actual journal size, temperature and duty.
For the referenced Johnson flanged system, support the shaft so it just touches the rubber without compressing it. Measure with a feeler gauge at the opposite side: contact at 6 o’clock means measurement at 12 o’clock. Record both ends where accessible and the ambient temperature. Shaft weight compressing the lining can produce a misleading result.
For smaller rubber-lined bearings, a two-point internal micrometer can deform the rubber; Duramax identifies plug gauges as the preferable bore check. Do not force a shaft through a tight bearing, and do not treat any visible movement as a universal replacement threshold.
On smaller screens, scroll the table sideways to read all columns.
| Record | Why it matters | Decision boundary |
|---|---|---|
| Shaft/journal diameter | Nominal and actual sizes can differ | Use the part-specific overshaft requirement |
| Both-end clearances | Wear or alignment can vary along the length | Do not average away a tight or damaged end |
| Temperature and support method | Rubber deformation changes the reading | Compare measurements under defined conditions |
| Water temperature and load | Catalogue calls for review above 95 °F (35 °C) lubricant temperature | Do not extrapolate its historical clearance values |
Water lubrication, dry running and the shaft seal
Keep the bearing wetted whenever the shaft rotates and keep the water grooves and bearing ends clear. A forward stern-tube bearing may need a forced feed where natural circulation is insufficient. Controllable-pitch operation also needs the installation’s water-flow assessment; merely being underwater does not demonstrate enough circulation.
For shaft insertion in the referenced Johnson flanged assembly, the instructions permit a suitable mild water-soluble soap or glycerin and exclude harmful additives. They specifically prohibit petroleum-based or non-water-soluble insertion lubricants because they can obstruct the water path. Oil-resistant rubber does not mean the bearing should be packed with grease.
A dripless shaft seal controls leakage into the vessel. The cutless bearing supports the shaft. Replacing one does not establish that the other is sound; identify them as separate assemblies. This guide does not substitute a seal-maintenance procedure.
Can the bearing be replaced without removing the propeller shaft?
Sometimes, for an accessible strut and a compatible split-collet tool. The Strut Pro manual describes collets around the shaft that press against the bearing shell, with a clearance opening for the old bearing. This does not prove access in an enclosed stern tube or every P-bracket. Measure shaft size, shell OD, bearing length and available tool space first.
Its manual calls for propeller removal and locating all bearing set screws, including screws hidden by paint or debris. Check that the receiving horseshoe clears the old shell and that the yokes remain square. Alternate the threaded rods progressively; the manually operated tool instructions prohibit an impact driver.
If the tool tightens but the bearing does not move, stop and recheck retainers, alignment, clearance and corrosion rather than increasing force. Do not load the rubber lining as if it were the metal shell. Homemade puller dimensions, hydraulic pressure and permitted strut loads are not established by this guide.
On smaller screens, scroll the table sideways to read all columns.
| Assembly | Possible method | What still needs checking |
|---|---|---|
| Accessible strut | Compatible around-shaft pressing tool | Collet/shell contact, exit space, retainers and tool capacity |
| Enclosed stern tube | Equipment-specific extraction, potentially shaft removal | Access, support and seal arrangement |
| Split/flanged bearing | Its own fastener and removal sequence | Joint, flange/pilot and alignment |
| Seized/corroded bearing | Reassess the cause and approved removal procedure | Do not sacrifice the shaft or housing to force a generic tool |
Installation limits: do not mix a tool manual with a bearing specification
Clean and inspect the housing and journal, verify the specified fit and retainers, and press with suitable support. Pounding, extreme cooling or an excessive interference can damage the rubber-to-shell bond. Numeric fit, bolt torque and final axial position must come from the exact assembly documentation.
On smaller screens, scroll the table sideways to read all columns.
| Instruction scope | Verified distinction | How to use it |
|---|---|---|
| Johnson sleeve catalogue | Gradual chilling limit on pages 4/6: −20 °F (−28 °C); no dry ice | This is the sleeve document, not the flanged limit |
| Johnson flanged installation | Page 3 gives 0 °F (−17.8 °C) as the chilling limit; no dry ice or shock | Use the document for the exact family; do not pick the colder value |
| Flanged housing press fit | Page 2 says not to lubricate the shell or housing for pressing | Do not transfer a tool maker’s generic shell-soap suggestion |
| Flanged shaft insertion | Page 3 permits specified water-soluble insertion lubricant | Shaft-to-rubber insertion and shell-to-housing pressing are different interfaces |
Is this a complete shipyard service manual?
No. It supplies identification, published dimensions and critical distinctions. Shaft support, lifting, alignment, retention, water supply and return-to-service checks remain specific to the vessel and bearing system.
Which material is best?
Choose from the approved installation, water conditions, shell strength, fit and lubrication requirements. Brass, non-metallic shells and other composite bearing systems do not share one universal fit or cooling rule.
What the evidence can — and cannot — tell you
| Observation or context | Interpretation to consider | Verification needed |
|---|---|---|
| Shaft | Actual journal diameter and units | 25 mm and 1 in (25.4 mm) are different sizes. |
| Housing | Bore, shell OD, length and retaining arrangement | Boat brand alone does not identify the installed bearing. |
| Construction | Brass or non-metallic sleeve; solid or split flange | Confirm the exact family before applying installation limits. |
| Operation | Water flow, shaft alignment, clearance and condition | Do not use a grease-filled rolling-bearing rule for a water-lubricated sleeve. |
A practical investigation sequence
Identify and record
Identify the installed bearing and record shaft diameter, shell OD, length, material, retaining screws/flange and water-feed arrangement. Use the shaft or sleeve diameter at the bearing journal, not an unrelated propeller dimension.
Check the context
Compare the matching manufacturer catalogue dimensions and inspect the shaft and housing. Record clearance, wear, alignment and water-path condition. Determine whether a strut tool can access the assembly or whether shaft removal is required.
Verify before acting
With the vessel and propulsion system safely secured and isolated, use the equipment-specific removal and installation procedure. Remove all retainers, support the shaft, use correctly sized pressing tools and stop if the assembly binds.
Keep the decision traceable
Check retention, alignment, running clearance and an unobstructed lubricating-water path after installation. Restore the propulsion assembly by its service instructions and complete the prescribed inspection before operation. Never run the bearing dry for a test.
Capture the information a model search cannot guess
Keep this checklist with your inspection or comparison. Checking a box only records that you have collected the item; it does not certify the bearing.
0 of 4 information groups recorded.
Technical basis & editorial scope
Original BearingScope workflow, written for catalogue research and comparison. Manufacturer material is used to check principles, not copied as a product endorsement or substituted for model-specific instructions. Reviewed 1 October 2026.
- Duramax Johnson Cutless selection catalogue: sleeve tables pages 4 and 6; clearance footnote page 19 — Exact manufacturer, product family and document scope only. Technical reference, not a vessel-fitment approval.
- Duramax Johnson Cutless flanged-bearing installation instructions, pages 2–4 — Exact manufacturer, product family and document scope only. Technical reference, not a vessel-fitment approval.
- Duramax Johnson Cutless water-lubricated bearing product families — Exact manufacturer, product family and document scope only. Technical reference, not a vessel-fitment approval.
- Duramax Johnson Cutless water-lubricated rubber-bearing construction — Exact manufacturer, product family and document scope only. Technical reference, not a vessel-fitment approval.
- Strut Pro manually operated tools: 2021 operating instructions, pages 7–14 — Exact manufacturer, product family and document scope only. Technical reference, not a vessel-fitment approval.
Source addresses and collection status are retained in the internal audit. No unpublished dimensions, torque settings, service intervals or interchange approvals are inferred.