Erg Split Book is an offline-first piece log for indoor rowers who finish a workout, read the monitor, and want those numbers saved in seconds—not paired to hardware and not locked behind a training-plan shop.

Open the app and land on a fullscreen boat-house list: stacked rows for every piece you have entered (2k, 5k, 30 min, interval sets, and more). Each row shows average split per 500 m, stroke rate, drag factor, and a feel chip so you can tell a strong piece from a grind at a glance.

Add a piece with presets for common distances and timed efforts, or enter a custom distance or time. Type split, rate, drag, notes, and optional interval breakdown rows exactly as the monitor showed them. When a new entry beats your stored best, the Personal Best board highlights it for that standard distance or timed piece—honest PBs built only from what you logged.

Stay on the list surface while you filter and sort by distance band, date range, drag factor, or feel tag. Open any piece for full stats, an interval table when you logged one, feel notes, and quick actions to duplicate the setup or mark a PB candidate. Choose a distance and scan the split trend strip: simple bars of your last average splits so you can see whether work is getting faster, entirely from local history.

First launch is not empty. A seed library of sample pieces (example 2k, steady-state 5k, interval sets) fills the list with a realistic boat-house so you can explore immediately. When you want data elsewhere, export piece history as plain CSV through the system share sheet—no account required. Preferences cover default drag factor, split display style, and list density. Everything stays on-device with local persistence. An optional home glance can show your latest piece split and active 2k PB.

No Bluetooth machine link. No sensors. No subscription plans. Just fast entry from the monitor readout, clear PBs per distance, filters that stay on the list, and split trends you can trust offline.