Identify Attwood SL33 and SL36 Boat Hatch Struts by MPN
Attwood hatch supports with matching black cylinders can carry different force ratings and lengths. Use the full number stamped on the support to distinguish a 15-inch SL33 from a 17.2-inch SL36. The spring's rated force and its compressed length matter as much as the visible extended size.
Clues on the original Attwood spring
SL33 identification
The SL33 items in this comparison extend to 15 inches and compress to 9.5 inches. The force number separates 20 lb and 40 lb versions.
SL36 identification
The SL36 group extends to 17.2 inches and compresses to 10.2 inches. Separate 30, 40 and 50 lb models share this geometry; the -1 and -5 versions remain distinct MPNs.
Hatch strut identification by exact number
| Attwood MPN | Family | Extended | Compressed | Stroke | Force | Fitting |
|---|---|---|---|---|---|---|
| SL33-20-5 | SL33 | 15 in | 9.5 in | 5.5 in | 20 lb | 10 mm socket |
| SL33-40-1 | SL33 | 15 in | 9.5 in | 5.5 in | 40 lb | 10 mm socket |
| SL36-30-1 | SL36 | 17.2 in | 10.2 in | 7 in | 30 lb | 10 mm socket |
| SL36-40-1 | SL36 | 17.2 in | 10.2 in | 7 in | 40 lb | 10 mm socket |
| SL36-50-1 | SL36 | 17.2 in | 10.2 in | 7 in | 50 lb | 10 mm socket |
| SL36-50-5 | SL36 | 17.2 in | 10.2 in | 7 in | 50 lb | 10 mm socket |
Different -1 and -5 versions have distinct complete manufacturer numbers. Match the actual marking and required package details rather than assuming suffixes can be ignored.
Inspect the part before replacement
- Hold the hatch open with a separate prop. A worn gas strut cannot be relied upon while it is removed.
- Locate the full Attwood MPN, including its SL prefix, force rating and final suffix.
- Measure the old spring in a safe condition and check the socket ends for cracking, distortion or missing retainers.
- Inspect the mounting ball studs and the hatch brackets; loose or damaged mounts must be corrected.
- Check the actual listing for condition and contents. UsedRVParts offers viewing and pickup by appointment in Kelowna.
Find the matching Attwood hatch strut
Open the individual listing to review its condition, photograph and supplied parts.
Need a longer support?
See our Attwood 20- and 23-inch support comparison to identify the other length family before replacing brackets or changing the hatch opening.
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