Overview

The Raymarine T221 is a wireless, solar-powered mast rotation transmitter for Raymarine Micronet wireless instrument systems on sailboats with rotating masts. It measures mast rotation angle and sends compensation data so the wind system can correct the apparent wind angle from a masthead wind transmitter as the mast moves.

This is a specialist instrument for performance sailing setups where mast rotation can otherwise make wind data misleading. It works on the Micronet wireless network, uses built-in solar panels to keep its internal battery charged, and is made for no-wires installation on the mast.

The system requires a Micronet display with compass setup capability, a Micronet Wireless Wind Transmitter, and a suitable heading source arrangement. That can be a T121 Hull Transmitter with a T909 Compass, or an STng heading source with a Micro-Talk Gateway.

Key features

• Compensates for rotating mast movement so wind angle readings stay useful when the mast is not fixed on the boat centerline.
• Uses Raymarine Micronet wireless networking, reducing the need to run wiring up or around the mast.
• Solar-powered with built-in panels that keep the internal battery pack charged during normal use.
• Compatible with Raymarine wireless instruments and intended for Micronet wind instrument installations.
• Fully waterproof, maintenance-free construction for exposed sailing installations.
• Supports calibration through a Micronet display with compass setup capability.

Installation and setup

The transmitter is mounted on the mast, with the bracket normally fitted to the front of the mast for the clearest radio path to the masthead wind unit. The mounting position should give the solar panels a clear view of the sky and should be free of magnetic disturbance.

Raymarine advises placing the bracket less than 1.5 m above the deck and keeping it within 15 degrees of vertical. Mast rake is acceptable as long as it remains under 20 degrees. The bracket can be fixed with non-magnetic rivets or self-tapping screws, or attached using the supplied Velcro strap arrangement.

System compatibility

This transmitter belongs in a Raymarine Micronet wireless wind system rather than a standalone GPS or chartplotter installation. Before fitting it, confirm that the boat already has the required Micronet wind and display hardware, plus the heading source needed for calibration and correction.

In a T121 and T909 system, the related hull transmitter wiring example uses 12 or 24 V DC with a 5 A inline fuse. In an STng heading source and Micro-Talk Gateway setup, the STng backbone uses its own 12 V power supply with a 5 A inline fuse shown in the example.

Use cases on board

The T221 is a good match for multihulls and performance sailboats where a rotating mast is part of the rig and accurate wind angle is important for trimming, racing, and repeatable sailing data. It is most relevant to sailors already using Raymarine wireless instruments who need their wind information to reflect the actual mast position, not just the apparent angle at the masthead.