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A castable sonar that finds fish before you cast a line

Pair it with your phone and see depth and structure from a belly boat, no separate display needed.

The Deeper Start pairs with a free smartphone app over its own Wi-Fi signal, showing depth and fish-holding structure on your phone screen — useful from any of our belly boats without mounting a separate display unit.

£165.34 inc. VAT
Fast, FREE United Kingdom delivery on all orders £75 or more. Orders under £75 pay a flat £5.99 delivery.

A castable sonar unit that pairs with your smartphone over its own Wi-Fi. Shows depth and fish-holding structure on the free Deeper app.

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castable sonar that pairsCastable sonar that pairs with a free smartphone app.
shows depth andShows depth and fish-holding structure before you cast.
no separate display unitNo separate display unit to mount — works from your phone.

Deeper Start Fish Finder, Portable Castable Sonar and Depth Finder

A traditional fish finder needs a separate display unit mounted somewhere on the boat, which is one more thing to fit and power on a belly boat that already has limited space. The Deeper Start sidesteps that entirely — it is a compact castable sonar that creates its own Wi-Fi signal and pairs directly with the free Deeper app on your phone.

Cast or lower it into the water near your position, and it shows depth and fish-holding structure on your phone screen in real time, letting you read the water before you commit to a spot rather than fishing blind. Over 2,900 buyers have rated it 4.3 stars, a solid track record for a first sonar unit.

It suits anyone moving into belly boat fishing who wants the advantage of locating structure and depth without adding a bulky, separately-mounted electronics setup to an already-loaded boat.

Specifications

BrandDeeper
TypeCastable Wi-Fi sonar, phone app-based
UseDepth and fish location from a boat, dock, shore or belly boat
PairingFree Deeper app, iOS and Android

Deeper Start Fish Finder, Portable Castable Sonar and Depth Finder

£165.34 inc. VAT

Free United Kingdom delivery · easy returns · secure checkout

Frequently Asked Questions

Do I need a separate screen or display?

No — it pairs directly with the free Deeper app on your smartphone over its own Wi-Fi signal, so your phone is the display. Nothing extra to mount.

How do I use it from a belly boat?

Cast or lower it into the water near your position and check the app for depth and structure readings — no fixed mounting is required, though our Deeper Flexible Arm can hold it in position if preferred.

Does it work on shore or from a kayak too?

Yes — it is built for use from a dock, shore, belly boat or kayak, not exclusively for one platform.

What does delivery cost and how long does it take?

Delivery cost and an estimate for your address are shown at checkout before you pay. Free delivery applies over the qualifying order value.

Can I return it if it is not right?

Yes — return it unused, with packaging where possible, under our returns policy for an exchange or refund.

Is checkout secure?

Card details are handled on Stripe or PayPal's own hosted pages and never touch our servers.

Reading the water before you cast: how a castable sonar actually helps

3 min read Float & Cast

Knowing what's beneath the surface before you cast changes how you fish a belly boat session, and a castable sonar is the most accessible way into that.

Why depth and structure matter from a belly boat

Bank anglers can often read a swim visually — depth changes, features, likely holding spots. From a belly boat sitting low on open water, that visual read is harder, which is exactly where a sonar reading fills the gap.

How a castable unit differs from a traditional fish finder

Traditional fish finders need a transducer mounted to the hull and a separate powered display — awkward on an inflatable belly boat. A castable unit like the Deeper Start skips both: cast it out, and it talks to your phone directly.

Reading the results sensibly

Treat the depth and structure readings as one input alongside your own knowledge of the venue, not a guarantee of fish. A sonar shows you what's there; it doesn't replace understanding how fish use that structure at different times of day.

Getting the most from your first sessions

Spend an early session or two just exploring readings across a familiar water before relying on it to pick new spots — learning to interpret what the app shows takes a little time, same as any new piece of kit.

Browse all belly boat accessories

Want to see what's under the water before you commit to a spot?

The Deeper Start turns your phone into a sonar display — no separate electronics to mount on your belly boat.

Still deciding? Ask us a question and we'll help you choose.

Page summary

The Deeper Start Fish Finder is a portable castable sonar unit that pairs with the free Deeper smartphone app over its own Wi-Fi signal, showing depth and fish-holding structure without needing a separate mounted display. Rated 4.3 stars from 2,976 reviews. Sold at Float & Cast.

Deeper Start Fish Finder, Portable Castable Sonar and Depth Finder £165.34