How TwinHull Index Works
Methodology, data sources, and assumptions behind every estimate.
1. Data Source
BoatValue is powered by a privately collected dataset of catamaran listings, tracked weekly from June 2024 through February 2026 (76 snapshots, ~1,000-1,400 listings per snapshot). Each record captures:
- Make and model
- Model year
- Length overall (LOA) in feet
- Asking price in USD
- Location and country
- Snapshot date (the week it was observed)
2. Fair Market Estimate
The estimate is computed in cascading levels — we start narrow and expand if there aren't enough comparable listings:
- Level 1: Same make + model, year within ±5 years
- Level 2: Same make + model, any year
- Level 3: Same make, similar length (±5 ft), year within ±10 years
- Level 4: Any make, similar length (±5 ft)
Once a pool of comparables is assembled, we compute:
- Point estimate: The median asking price of the comp pool (year-adjusted if enough per-year data exists)
- Confidence band (low-high): 25th-75th percentile of the comp pool
- Top factors: Plain-English notes on what drives the estimate
Estimates use all listed boats in the comp pool. The "NEW" flag in our dataset indicates a listing that first appeared this week — it does not indicate boat condition.
3. Comparable Boats
Each comp listing is scored 0-100 based on similarity to your query:
| Attribute | Points |
|---|---|
| Exact model match | +35 |
| Same make (no model match) | +10 |
| Year within ±2 | +15 |
| Year within ±5 | +8 |
| Length within ±1 ft | +15 |
| Length within ±3 ft | +10 |
| Length within ±6 ft | +4 |
| Same country | +5 |
Only listings with a similarity score ≥ 10 are returned. Top 12 are shown by default.
4. Market Trends
For each of the 76 weekly snapshots, we compute the median, 25th, and 75th percentile asking prices for the selected segment (overall market, a specific make/model, or a length band). The result is a time series showing how the market has moved week over week.
Snapshots with fewer than 2 matching listings are excluded from the chart. Early snapshots (June 2024) use a different data schema and may show fewer listings in narrow segments.
5. Known Limitations
- No cabin/berth count: This field is not available in the dataset. Cabin layout (3-cabin vs. 4-cabin of the same model) can affect price significantly.
- No condition data: We cannot differentiate a pristine, well-equipped boat from a project boat of the same year and model.
- Asking price only: Final sale prices are typically 5-15% below asking.
- US-centric volume: ~19% of listings are in the USA, which is the largest single market. European and Caribbean prices may differ from US market.
- Thin segments: Rare makes/models may have very few comps, leading to wider confidence bands or fallback to length-based estimates.
- Currency: All prices normalized to USD. Exchange rate fluctuations affect non-USD listings over time.