About

Daiwa line counter reels display a unitless number from 0 to 999 that does not correspond linearly to feet or meters of line deployed. The counter increments per spool revolution, but each revolution pays out less line as the effective spool radius r shrinks with depletion. A reading of 50 on a fully spooled reel releases a different length than 50 on a half-empty spool. Ignoring this non-linearity leads to incorrect trolling depths, missed target zones, and inconsistent catch logs. This tool models the spool as an annular cylinder and simulates unwinding layer by layer to produce an accurate counter-to-depth conversion table for your specific reel, line diameter, and fill level.

The calculation depends on three physical parameters: spool lip radius R, arbor radius r, and spool width L. Line diameter d determines how many wraps fit per layer and how many layers fill the spool. This tool approximates real geometry assuming uniform winding under moderate tension. Actual deployment may vary 3 - 8% due to uneven winding, line stretch under load, and guide friction. For braided lines with near-zero stretch, accuracy improves. For monofilament at depth, consider stretch compensation.

Formulas

The spool is modeled as an annular cylinder. Total line length is computed by summing the circumference of each wrap across all layers from the arbor outward to the lip.

N_wraps/layer = Ld

where L = spool width and d = line diameter.

N_layers = R − rd

where R = spool lip radius and r = arbor radius.

For layer i (counting from 0 at the arbor), the effective radius of that layer is:

r_i = r + (i + 0.5) × d

Each wrap on layer i deploys 2πr_i of line. The counter increments once per spool revolution, which corresponds to N_wraps/layer wraps (assuming a level-wind mechanism distributes evenly across the spool width per revolution). Line deploys from the outermost layer inward. As each layer is consumed, r_i decreases, so each counter tick represents less line. Total line deployed at counter reading C:

D(C) = C∑t=1 2π ⋅ r_eff(t) ⋅ N_wraps/layer

where r_eff(t) is the effective radius at counter tick t, which steps down by d each time a full layer is consumed. One counter tick = one spool revolution = N_wraps/layer wraps laid side by side across the spool width.

Reference Data

Reel Model	Spool Width mm	Lip Radius mm	Arbor Radius mm	Gear Ratio	Counter Ticks/Rev	Mono Capacity	Braid Capacity
Sealine SG27LC3B	42	31	19	5.1:1	1	14lb/300yd	40lb/440yd
Sealine SG47LC3B	52	37	22	5.1:1	1	20lb/350yd	65lb/460yd
Sealine SG57LC3B	56	40	24	5.1:1	1	25lb/380yd	80lb/500yd
Accudepth Plus 27LCB	42	31	19	4.2:1	1	14lb/300yd	40lb/430yd
Accudepth Plus 47LCB	52	37	22	4.2:1	1	20lb/350yd	65lb/450yd
Accudepth Plus 57LCB	56	40	24	4.2:1	1	25lb/390yd	80lb/510yd
Lexa-LC 300	38	28	17	6.3:1	1	12lb/270yd	30lb/380yd
Lexa-LC 400	42	33	20	5.5:1	1	17lb/310yd	50lb/420yd
Saltist LC 20	38	28	17	6.4:1	1	12lb/260yd	30lb/370yd
Saltist LC 30	42	31	19	6.4:1	1	14lb/310yd	40lb/440yd
Saltist LC 40	48	35	21	6.4:1	1	17lb/330yd	50lb/470yd
Saltist LC 50	56	40	24	6.4:1	1	25lb/390yd	80lb/500yd
Daiwa 47LCBL	52	37	22	5.1:1	1	20lb/350yd	65lb/450yd
Daiwa 17LCBL	34	27	16	5.1:1	1	10lb/220yd	20lb/310yd
Daiwa 27LCBL	42	31	19	5.1:1	1	14lb/300yd	40lb/430yd

Frequently Asked Questions

Thicker line fills the spool with fewer total wraps. A fully spooled reel with 0.40 mm mono has a larger effective starting radius than one spooled with 0.20 mm braid, so each revolution pays out more line initially. However, the thicker line also depletes the spool faster per layer, causing the radius to shrink more rapidly. The net effect: thicker line yields a different (usually shorter total but initially longer per-tick) counter-to-depth curve. Always recalculate when changing line.

Under controlled conditions (uniform winding, consistent tension, no line memory effects), the geometric model is accurate to within 3-5%. Real-world factors that introduce error include: uneven level-wind distribution, line stretch under trolling load (monofilament can stretch 10-25%), line compressing under tension on lower layers, and partial spool fills. Braided line with near-zero stretch and uniform diameter produces the most accurate results.

Always calibrate and compute from a full spool. The calculator assumes line fills from the arbor to the lip radius. If your spool is only 80% full, the effective starting radius is smaller, and every counter reading will overestimate depth. If you cannot fill completely, measure the actual outer line radius with calipers and enter it as a custom lip radius to compensate.

No. Daiwa line counters are mechanically coupled to the spool shaft, not the handle. One counter tick equals one spool revolution regardless of gear ratio. The gear ratio affects how many handle turns produce one spool revolution, but the counter tracks spool rotations directly. A 5.1:1 and a 6.3:1 reel with identical spool dimensions and line will produce identical counter-to-depth tables.

Enter only the arbor radius and the diameter of your main line. The backing effectively increases the arbor radius. Measure the radius of the spool after the backing is wound on (use calipers across the diameter, divide by 2) and enter that as your arbor radius. The calculator will then correctly model only the main line portion that deploys during fishing.

Each manufacturer uses different mechanical gearing between the spool shaft and the counter dial. Some counters tick once per revolution, others use reduction gears producing fractional ticks. Additionally, spool dimensions differ between brands. A reading of 100 on a Daiwa Sealine SG47 deploys a completely different length than 100 on an Okuma Magda. Never cross-reference counter readings between brands or even between different models of the same brand.