Methodology
How we decide whether a cart fits
Every verdict on this site comes out of one rules engine. This page publishes that engine in full — the evidence grades, the load maths, the terrain scale and the safety gates — so you can check our reasoning instead of trusting our conclusion.
What we do not do
We have not pull-force tested these carts. We own no dynamometer data, and we have not dragged every cart across every surface. Terrain scores on this site are a declared judgement scale built from manufacturer specifications, wheel geometry and documented owner experience — not instrumented measurement. Where we have tested nothing, we say so on our testing status page.
1. Evidence grades
Every technical figure and every compatibility statement on this site carries one of six grades. Nothing is published without one. A grade describes where the claim came from, not how much we like it.
The figure or fit statement is published by the manufacturer of the kayak or the cart, in their own documentation, spec sheet or support channel.
We physically performed the fit or the measurement ourselves and recorded the method, date and conditions. We currently publish no staff-tested records — see our testing status page.
Three or more independent owners, in separate public sources, describe the same outcome. Sources are listed on the record.
One identifiable public owner account. Directional evidence only — treat as a lead, not a fact.
No direct fit report exists. Our published rules engine compared measured cart geometry and capacity against measured kayak geometry and loaded weight. Geometry is not the same as a real-world fit.
Sources disagree, or the only sources are retailer listings that contradict each other. We show the conflict rather than pick a winner.
Inheritance rule
A compatibility verdict can never be graded more strongly than the weakest figure it depends on. A pairing built on an inferred hull width is an inferred pairing, even if every other input is manufacturer confirmed.
2. Capacity: headline vs planning
Cart capacity is the least trustworthy number in this industry. The same SKU is routinely listed at several different ratings across retailers, and headline figures often describe flat ground with no shock loading. So we hold two numbers.
Headline capacity
The best-case number the manufacturer publishes. We use it for coarse filtering only. It is never the number your load bar is measured against.
Planning capacity
The conservative number we actually calculate with: the lowest published terrain-specific variant if one exists, otherwise the lowest credible figure across sources.
Worked example — the C-Tug capacity dispute
The Railblaza C-Tug is cited at 170, 175, 260, 265 and 300 lb depending on where you look. Our working hypothesis is that this is wheel-dependent, but the manufacturer pages we tried returned 404 and we could not confirm it. So the C-Tug’s planning capacity in our database is null, and the finder returns “Not enough data” for it rather than picking a flattering number. That is the correct answer to an unresolved question.
Where a capacity is disputed but we can still justify a conservative planning figure, we use it and attach a permanent provisional capacity warning to every verdict that depends on it.
3. Load-margin bands
Your load is your kayak’s rigged weight plus everything you cart with it, expressed as a percentage of planning capacity.
| Band | % of planning capacity | What it means |
|---|---|---|
| Comfortable | 0–70% | Under 70% of rated capacity. Headroom for gear creep, rough ground and shock loading. |
| Moderate | 70–85% | 70–85% of rated capacity. Fine on firm ground. Watch for frame flex over kerbs and roots. |
| Near maximum | 85–100% | 85–100% of rated capacity. No margin for shock loads. Avoid drops, kerbs and stairs. |
| Exceeds rating | Over 100% | Over the manufacturer rating. Do not use. Frame, axle or wheel failure under load is a real injury risk. |
4. The terrain scale
Published verbatim, because a number without its definition is meaningless. Each cart is scored per surface using the best wheel available for that cart. This is a judgement scale, not a measurement.
Score 1
Effectively fails. The wheel ploughs in and the cart stops being a cart.
Score 2
Hard work. Expect to drag rather than roll over any distance.
Score 3
Usable but you will feel it. Fine for short distances.
Score 4
Works well. Minor extra effort.
Score 5
Rolls easily. This is what the wheel is for.
The surfaces we score against are: Sealed car park / boat ramp, Hard-packed dirt track, Grass / turf, Gravel or shingle, Wet / firm sand, Deep dry soft sand, Mud / tidal flat, Steps or a steep bank.
5. The scupper safety gate
Scupper holes are drainage, not structure
Scupper holes are moulded to let water out. Very few are engineered to carry the weight of a loaded boat. Hobie state plainly that cart damage to scuppers is not a warranty issue, and the damage pattern — radiating stress cracks around the hole, deformation of the surrounding plastic — is immediately recognisable to a dealer as user-caused.
Our rules, applied in order:
- A scupper cart is never presented as safe merely because the posts physically fit the holes.
- Where a kayak’s policy is platform-only, scupper carts are blocked for that boat. This covers heavy pedal boats and large fishing platforms.
- Where a kayak’s policy is platform-preferred, scupper carts are permitted but always carry a caution.
- Where scupper structural reinforcement is simply not published, we warn. We never assume an unlisted scupper is reinforced.
- Posts must be fully inserted with the collars seated so the crossbar — not the hole rim — carries the load. A keeper pin stops posts bouncing out on rough ground.
- Bulging around a scupper under load is the stage before cracking. Stop using the cart at that point.
- Never leave a loaded boat parked on scupper posts.
6. The eight evaluation steps
This is the order the Cart Finder runs in, every time, for every pairing.
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Weight against planning capacity
We add your kayak’s rigged weight to the gear you tell us you cart, then divide by the cart’s planning capacity — not its headline capacity. Over 100% is a hard blocker. 85–100% raises a "near maximum" warning. Where a cart’s capacity is disputed between sources, we also attach a "provisional capacity" warning so you know the denominator itself is uncertain.
-
Hull shape against pad geometry
A flat pad under a rounded or displacement hull contacts a narrow strip instead of a broad surface. We hold a hull-shape list per cart and warn when your hull is not on it. Pontoon and tunnel hulls are treated separately because stance width matters more than pad shape on those boats.
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Known non-fits
Where a specific kayak is documented as not fitting a specific cart, that pairing is a hard blocker regardless of how the numbers look. Token matching is exact — we do not extrapolate a non-fit from one model to its siblings.
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The scupper safety gate
Scupper carts load the hull through holes that were moulded to drain water, not to carry a boat. Where a manufacturer advises against a scupper cart, or where the kayak is heavy enough that we judge the risk unacceptable, a scupper cart is blocked outright. Where scupper structure is simply not published, we warn rather than assume it is fine.
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Terrain
We score every cart’s wheel options against your launch surface on the 1–5 scale below, taking the best wheel available for that cart. A score of 1 is a blocker. A 2 is a warning. A 4 or 5 is recorded as a positive reason.
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Rudder, drive and transducer interference
Pedal drives, rudders, transducer shields and moulded consoles all restrict where a cart can sit. We hold per-kayak interference notes and surface them on any pairing where cart placement is constrained.
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Saltwater and storage
If you launch in salt, a cart with corrodible structural parts earns a warning, and a cart whose corrosion behaviour is undocumented earns a softer one. If you need the cart to pack into the boat, a cart that neither folds nor disassembles is blocked for that use.
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Confidence, then verdict
Each pairing inherits the weakest evidence grade underneath it, and is downgraded to unverified if the cart’s capacity is disputed or missing. Any blocker means Not recommended. Missing weight or capacity means Not enough data — never a pass. Two or more material warnings means Caution, one means Workable, none means Recommended.
7. How warnings become a verdict
Five warning types are counted as material — meaning they are serious enough to move a verdict on their own:
- hull_shape
- near_max
- terrain_poor
- scupper_caution
- salt
| Verdict | Triggered when |
|---|---|
| Not recommended | Any blocker fires — over capacity, a known non-fit, a blocked scupper cart, a terrain score of 1, or a cart that cannot pack when packing is required. |
| Not enough data | Your kayak’s loaded weight or the cart’s capacity is unknown. We refuse to guess. Unknown is never treated as fine. |
| Caution | Two or more material warnings. |
| Workable | Exactly one material warning. |
| Recommended | No blockers and no material warnings. |
8. Things we will not do
- Invent a dimension. If a manufacturer has not published a scupper diameter, our database says "not published" and the finder behaves accordingly.
- Claim hands-on testing we did not perform.
- Treat "universal fit" as evidence of fit. It is a marketing phrase.
- Assume a scupper hole is structural because a cart post fits it.
- Calculate with hull weight when the boat is used rigged.
- Recommend a cart whose capacity your load exceeds, for any reason.
- Recommend a scupper cart where the kayak manufacturer advises against one.
- Let a commercial relationship outrank a hull-safety or fit judgement.