Rudder Port Bearings & Seals

IMPERIAL SIZE RUDDER PORT BEARING TYPE D Replacement Bearing and Seal Only (Does Not Include The Liner)

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Tides Marine

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Price $560.97


RPBH-D-2250-00 – Tides Marine Rudder Port Bearing Type D for a 2 1/4 inch rudder stock.

Replacement Bearing and Seal.

The Tides Marine Type-D rudder port is an integrated approach to rudder port installation. It is for boats constructed of FRP. It can be used for new boat construction and is also easy to use as a retrofit for replacing other types of conventional rudder ports. No tooling is required.

The Type-D is a sealed bearing consisting of a UHMW housing with a nitrile rubber lip seal. It eliminates metal-to-metal abrasion and electrolytic corrosion.

The Type-D kit includes the bearing housing, which has a threaded OD, and a matching epoxy FRP “liner”.

The liner can be laminated into an opening in the hull. Once the liner is laminated into the boat structure, it provides a preformed cavity matching the bearing profile. The bearing can then be threaded in and out for easy removal or replacement.

New Construction – Component Overview

The Tides Marine Type D system components include a FRP liner and the Type D bearing and seal.

Molded from FRP and compatible with polyester, vinylester and epoxy systems, each Type D liner has an internal thread to accept its corresponding rudder bearing and seal.

The Type D rudder bearing and seal assembly consists of a one-piece UHMW housing with a nitrile lip seal. The UHMW bearing eliminates metal-to-metal contact and associated problems of abrasion and electrolytic corrosion. They are 100% watertight. Their performance characteristics match those of other Tides Marine rudder ports in that they are quiet, smooth and vibration free.

Mold Installation Types

Type 1: Molds with an existing “flat” at the rudder port location. This installation will use the standard flange-type liner.

Type 2: Molds which require modification to achieve a “flat” surface or pocket for mounting a standard flange-type liner.

Type 3: Molds which require modification to accept an angled liner to match dead rise and rocker angles.


To determine which Type D to order, all you need is the exact diameter of your rudder stock (.000”). Assembly specifications are detailed in the Imperial and Metric Size pages. Confirm clearances and determine what, if any, mold modifications will be necessary. If necessary, please contact Tides Marine to discuss your installation parameters before placing your order.

RPB Type D Imperial Sizes Specifications (dimensions in inches)

New Installations, Choose Part Number Includes liner

Replacement Bearings with Seal, Choose Part Number Without liner

Rudder Stock OD – A Flange Diameter – B Thread Diameter – C Flange Height – D Thread Height – E Base Length – F Retaining Ring Part Number Includes tdner Part Number Without tdner
1 3 2 1/2 1 1/2 2 11/16 1 9/16 185 RPB-D-1000-00 RPBH-D-1000-00
1 1/4 2 2 1/2 1 1/2 2 11/16 1 9/16 206 RPB-D-1250-00 RPBH-D-1250-00
1 3/8 3 2 1/2 1 1/2 2 11/16 1 9/16 212 RPB-C-1375-00 RPBH-C-1375-00
1 1/2 4 3 1/4 1 1/2 2 15/32 1 13/16 250 RPB-C-1500-00 RPBH-C-1500-00
1 3/4 4 3 1/4 1 1/2 2 15/32 1 13/16 250 RPB-D-1750-00 RPBH-D-1750-00
2 4 1/2 3 1/2 1 3/4 2 15/32 2 1/16 300 RPB-C-2000-00 RPBH-C-2000-00
2 1/4 4 1/2 3 1/2 1 3/4 2 15/32 2 1/16 325 RPB-D-2250-00 RPBH-D-2250-00
2 1/2 5 4 1/4 1 3/4 2 15/32 2 9/16 350 RPB-D-2500-00 RPBH-D-2500-00
2 3/4 5 4 1/4 1 3/4 2 15/32 2 9/16 375 RPB-D-2750-00 RPBH-D-2750-00
3 6 5 1/4 1 1/2 2 15/16 2 13/16 400 RPB-D-3000-00 RPBH-D-3000-00
3 1/2 6 5 1/4 1 1/2 2 15/16 2 13/16 450 RPB-D-3500-00 RPBH-D-3500-00
4 6 1/2 5 1/2 1 1/2 2 15/16 3 13/16 500 RPB-D-4000-00 RPBH-D-4000-00
4 1/4 6 1/2 5 1/2 1 1/2 2 15/16 3 13/16 525 RPB-D-4000-00 RPBH-D-4000-00
4 1/2 6 1/2 5 1/4 1 1/2 2 15/16 3 13/16 550 RPB-D-4500-00 RPBH-D-4500-00

Tide Marine offers many custom sizes and dimensions. Please call for any size or dimension you do not see here.

RPB Type D Metric Sizes
Specifications (dimensions in inches except rudder stock OD)

Rudder Stock OD – A Flange Diameter – B Thread Diameter – C Flange Height – D Thread Length – E Base Length – F Retaining Ring Part Number Includes Liner Part Number Without Liner
25MM 3 2 1/2 1 1/2 2 11/16 1 9/16 150 RPB-D-25MM-00 RPBH-D-25MM-00
30MM 3 2 1/2 1 1/2 2 11/16 1 9/16 181 RPB-D-30MM-00 RPBH-D-30MM-00
40MM 3 3 1/4 1 1/2 2 9/64 1 13/16 250 RPB-D-40MM-00 RPBH-D-40MM-00
The following is a description of the installation procedures associated with a “Type One” installation. Installation instructions are included with each unit and should be followed closely.

Mold Instructions

  1. Locate the exact position of the rudder stock center in the mold surface.
  2. Carefully drill a small pilot hole through the mold. Re-drill the hole, this time, slightly larger than the diameter of the threaded rod which Tides will supply.
  3. From inside the mold, pass the threaded rod through the hole and screw it into the aluminum block lo­cated outside the mold.
  4. Align the threaded rod (on the inside of the mold) so that its axis matches the desired axis of the rudder.
  5. Temporarily affix the threaded rod in position until the aluminum block can be glassed in place. Note: Some reshaping of the block may be required to ensure that it contacts this side of the mold in the most secure manner.
  6. Bond the aluminum block to the mold.
  7. Remove the threaded rod and build up the required flat area on the mold surface to accommodate the flange of the Type-D liner and create the desired surface transitions. Use proper mold materials and techniques. If another length of threaded rod is inserted into the aluminum block before starting this “build-up”, it will help keep the hole in the mold clean and “in reference”.


Liner Installation Prior to Lay-Up

  1. Prepare the liner for lay-up by roughing the outer surfaces with a grinder and wipe clean with thinner.
  2. Screw the UHMW plug into the liner until the bottoms are flush.
  3. Mask the top of the assembly to protect it from over­spray/excess resin.
  4. Locate the assembly against the mold surface and bolt in place through the hole in the mold.


Lay-Up Procedure

  1. Begin the hull lay-up in the normal manner.
  2. Cut an X in the cloth above the liner so that it can be laid down and around the flange base with tabs against the outer wall of the liner.
  3. On subsequent layers, stagger the position of the X cuts so that the tabs overlap each other.
  4. Lay-up should radiate out away from the tube at least two times the diameter of the liner.
  5. Before removing the hull from the mold, remove the plug bolt. Leave the UHMW plug in the hull until it is time to install the rudder.


Installation of Type-D Assembly

  1. Remove the UHMW plug from the liner.
  2. Inspect the interior shoulder of the liner. Confirm that there is no resin on the shoulder and that it is clean and free of dust and debris.
  3. Confirm that the “O” ring under the shoulder of the Type-D Assembly is in place. Add a bead of marine sealant (such as Lifecaulk™ or 3-M™ 101) to this area.
  4. Thread the Type-D assembly into the liner until the bottom of the assembly is flush with bottom of the hull. In this position, the “O” ring will be sufficiently compressed, resulting in a watertight fitting.
  5. Tighten firmly with a strap wrench.

NOTE: Before installing the rudder, insert the red installation hat into the lip seal. When rudder is in place, remove, invert and replace it on top of the Type-D unit to keep debris off the lip seal during use.



Complete Type-D Installation Guide may be downloaded HERE

Lead Times Update:

Due to increases in demand, current lead times have been extended.

Standard SureSeals and Rudder Bearings not in stock: 10-12 business days
Standard Upper Bearings not in stock: 12-15 business days
Custom Parts (excluding Sailtracks): 28 business days

Sailtracks: 3-5 business days

We appreciate your understanding.

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