Upwind Technique in Waves — RS21 and Oh! (Olson 30)
The Physics — What Waves Actually Do to an Upwind Boat
When sailing upwind, the boat and waves are moving toward each other. The bow hits the wave face. The wave does not push the boat forward — it slows the boat down.
The wave face is a braking event. Speed drops. The bow pitches up. Because the boat has slowed, apparent wind softens and swings aft.
Heading up into softened apparent wind stalls the sails at exactly the moment the boat needs power to re-accelerate. This compounds the speed loss.
“Chop can stop you dead in your tracks if you feather up in fresh breeze.” — North Sails, Steering Upwind
The correct response to a wave hit is to maintain or restore power, primarily through sail trim.
Two Wave Types — Different Responses
| Wave type | What happens at the face | Correct response |
|---|---|---|
| Short chop (1’–2’) | Boat hits wave. Braking force. Speed drops. Apparent wind goes aft. | Sail trim first. Keep power on. Bear off slightly if bow is being stopped. |
| Organised swell (2’+ with clear face and back, long period) | Hull rises gradually up a long slope. Bow pitch is gentle. The effective sail angle shifts slightly as the hull rises. | Heading up a degree or two on the face can capture that angle shift. Bear away on the back to restore drive. |
The traditional “head up on face / bear away on back” sequence describes the swell scenario. It was incorrectly applied to short chop in the original session notes. This document corrects that.
Short Chop (1’–2’, 8–15 kts) — Both Boats
Sail trim is the primary tool. The helm holds a groove.
“If the boat is well trimmed it will find its own best path through the waves. You can help by playing the traveler (or sheet if vang sheeting) rather than steering with the rudder.” — North Sails, Depowering & Powering-Up
Priority Order
| Priority | Tool | Purpose |
|---|---|---|
| 1st | Sail depth (fuller) | Power to punch through each wave hit and re-accelerate |
| 2nd | Sail twist (more) | Wider groove — consistent power as the boat pitches and yaws |
| 3rd | Traveller / mainsheet (active) | Primary power control — no rudder drag |
| 4th | Flat boat | Upright hull punches better. Heel creates weather helm and drag. |
| 5th | Bear off slightly | When a larger wave is about to stop the boat — add angle of attack, keep bow from burying, maintain drive through the hit |
| Last | Heading up | Only for the larger waves in a set where a clear face exists. Not for every 1’–2’ ripple. |
What “Heading Up” Still Does in Chop
There is one valid use of heading up in short chop: reducing impact angle on a wave that would otherwise stop the boat square. A slight luff as the bow meets a larger crest helps the bow slice upward rather than slam horizontally into the face. This is impact management — not harvesting lift from the wave, which the physics does not support.
What to Avoid
Feathering up repeatedly into every chop hit. Each time the boat has just been slowed, heading up removes power at the worst moment. In 1’–2’ chop this is the most common VMG-killing habit.
Organised Swell / Larger Waves (2’+)
As waves grow with a clear face-and-back structure, the dynamics change. The face is gradual enough for the hull to ride rather than just impact.
On the face: Steer 1–3° toward the wind. As the bow rises on a long face, the effective angle between the sails and apparent wind shifts. Capturing that shift with a small heading change adds VMG. Hold power on — don’t over-trim.
At the crest: Smooth transition. Begin bearing away.
On the back: Bear away. The boat will slow as the wave passes. Bearing away maintains drive and rebuilds speed for the next face.
This is the traditional head-up/bear-away sequence. In swell conditions it has genuine validity. The magnitude of heading change depends on wave size — bigger waves, more degrees.
Sail Trim Setup for Chop
Set these before engaging waves — not reactive, proactive.
| Control | Flat water setting | Chop adjustment | Why |
|---|---|---|---|
| Sail depth (main + jib) | Moderate | Fuller | Power to punch and re-accelerate |
| Twist (main leech, jib) | Less | More | Wider groove through pitch |
| Traveller | Near centreline | Active — ready to ease with heel or puffs | Manages power without rudder |
| Jib lead | Normal | Slightly forward | Maintains depth when sheet is eased |
| Jib sheet | Normal | Slightly eased | Depth + twist combination |
Active Trim Through a Wave Sequence (short chop)
| Situation | Helm | Jib | Traveller |
|---|---|---|---|
| Normal chop — between hits | Hold groove | Hold | Hold base position |
| Chop hit — bow slows and pitches up | Hold or slight bear away | Hold — keep power on | Hold or slight ease to prevent stalling |
| Larger wave approaching | Bear off a degree or two | Ease slightly — add power | Ease slightly |
| After large wave — speed rebuilding | Return to groove | Trim in as speed builds | Return to base |
The trimmer is active continuously. The helm is largely holding a consistent angle. This is the opposite of the original session framing, which put the work primarily on the helm.
RS21 (Sportboat) — Specific Notes
- Light hull, 480 kg — every wave hit is felt immediately. Speed loss is abrupt.
- Rudder drag is very costly on the narrow hull. Fewer and smaller helm inputs is always faster.
- A correctly trimmed RS21 handles most 1’–2’ chop without needing steering corrections.
- The boat is reactive — it will find its groove quickly when properly trimmed.
- In short chop: trim for power, hike hard, traveller active, minimal helm.
- In larger waves (2’+): active face/back steering becomes worthwhile. The RS21’s reactivity becomes an asset — it responds quickly to each input.
RS21 and the J70 comparison: North Sails’ J70 guide (most comparable sportboat) focuses on heel angle control (14–17°), weight placement aft in chop, and maintaining a narrow groove — not on wave-by-wave steering. Same principles apply to RS21.
Oh! (ULDB Olson 30) — Specific Notes
- 9.1m waterline spans multiple 1’–2’ chop crests simultaneously. The hull naturally averages short chop.
- 910 kg — more momentum. Individual wave hits produce less speed variation.
- Active wave steering in 1’–2’ chop adds more rudder drag than it saves in VMG.
- The Olson 30 groove is the primary VMG tool in short chop. Consistent angle slightly lower than flat water optimum.
- Class mantra — low and fast — is partly a chop response: maintain speed and groove rather than fighting waves.
- In 2’+ organised swell: face/back steering becomes worthwhile, applied to the larger sets.
Both Boats — Wave Size Threshold
| Wave size | RS21 | Oh! (ULDB) |
|---|---|---|
| 1’–2’ short chop | Trim + groove primary. Selective steering for larger waves in the set. | Trim + groove primary. Very minimal steering. |
| 2’–3’ with clear faces | Active steering worthwhile on significant waves. | Active on the largest sets. |
| 3’+ organised swell | Head up on face / bear away on back — full technique, active on every wave. | Same. Longer waterline means smoother transition, technique is active but less frantic. |
Vakaros Atlas 2 Integration
The Atlas 2 is well-placed to settle this empirically. Log VMG comparing:
- Trim-first approach — groove sailing, minimal helm, traveller active
- Active wave-steering — heading up on every face
The real-time VMG readout will show which produces results for the specific wave conditions on the day. Conditions vary. Test both. Trust the data.
Next Topic Flagged
Crew weight placement and fore-aft trim in chop.
Sources
- North Sails, Depowering & Powering-Up: https://www.northsails.com/blogs/north-sails-blog/techniques-for-de-powering-in-heavy-air-and-powering-up-in-light-air
- North Sails, Steering Upwind: https://www.northsails.com/blogs/north-sails-blog/steering-upwind
- North Sails, J70 Upwind Tips for Big Breeze and Chop: https://www.northsails.com/blogs/north-sails-blog/j70-upwind-tips-for-big-breeze-and-chop
- Original Claude Chat session: 2026-05-23 — starting point, substantially revised through physics review in this session