Underwater Gear

Keep your boat running smooth and tracking true with precision underwater gear from WaterSkis.com. Whether you're replacing a worn Mastercraft drive shaft, upgrading a Moomba rudder, or sourcing an exact-fit Supra strut, we carry genuine OEM and compatible parts built to match factory performance. This category includes critical inboard components like drive shafts, struts, rudders, and other hardware essential to your boat’s handling and power delivery.

Need to find the right part fast? Use our Boat Part Lookup Tool to identify inboard boat underwater gear for your exact year, make, and model—no guesswork required. We stock parts for top ski and wake brands, including Mastercraft, Moomba, and Supra, with quality you can trust in deep water or shallow turns.

For smooth rides and confident control, trust WaterSkis.com for the underwater gear that keeps your boat performing its best.


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  • MasterCraft OEM Drive Shaft 48 1/8" - 321 MasterCraft OEM Drive Shaft 48 1/8" - 321

    MasterCraft OEM Drive Shaft 48 1/8" - 321

    MasterCraft
    $749.99
    MasterCraft OEM Drive Shaft 48 1/8" - 321 This genuine MasterCraft drive shaft is 48-1/8 inches long by 1-1/8 inch diameter and is splined. Comes with a new prop nut and cotter pin. Designed for boats with a splined drive shaft.   **The images are of...
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    $749.99
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  • MasterCraft OEM Drive Shaft 47.5" - 320 MasterCraft OEM Drive Shaft 47.5" - 320

    MasterCraft OEM Drive Shaft 47.5" - 320

    MasterCraft
    $833.99
    MasterCraft OEM Drive Shaft 47.5" - 320 This genuine MasterCraft drive shaft is 47.5 inches long by 1-1/8 inch diameter and is double splined. This drive shaft is specifically designed for MasterCraft Boats. Comes with a new prop nut and cotter pin...
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    $833.99
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  • MasterCraft OEM Drive Shaft 51" - 328 MasterCraft OEM Drive Shaft 51" - 328

    MasterCraft OEM Drive Shaft 51" - 328

    MasterCraft
    $939.99
    MasterCraft OEM Drive Shaft 51" - 328  This genuine MasterCraft drive shaft is 51 inches long by 1-1/8 inch diameter with a 4inch coupler and is double splined. Comes with a new prop nut and cotter pin. Designed for boats with a splined drive shaft...
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    $939.99
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  • MasterCraft OEM Drive Shaft 49.5" - 323 MasterCraft OEM Drive Shaft 49.5" - 323

    MasterCraft OEM Drive Shaft 49.5" - 323

    MasterCraft
    $1,049.99
    MasterCraft OEM Drive Shaft 49.5" - 323  This genuine MasterCraft drive shaft is 49 and one half inches long by 1-1/8 inch diameter and is double splined. Comes with a new prop nut and cotter pin. Designed for boats with a splined drive shaft.   **The...
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    $1,049.99
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  • MasterCraft OEM Drive Shaft 49" - 322 MasterCraft OEM Drive Shaft 49" - 322

    MasterCraft OEM Drive Shaft 49" - 322

    MasterCraft
    $833.99
    MasterCraft OEM Drive Shaft 49" - 322 This genuine MasterCraft drive shaft is 49 inches long by 1-1/8 inch diameter and is double splined. Comes with a new prop nut and cotter pin. Designed for boats with a splined drive shaft.   **The images are of a...
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    $833.99
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  • MasterCraft OEM Tracking Fin - 190

    MasterCraft
    $244.99
    MasterCraft OEM Tracking Fin- 190 This genuine MasterCraft OEM Tracking is model specific. If you have damaged your rudder Tracking Fin it is typical that you have with other Under Water Gear damage. Use the Parts Finder to select your year make and...
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    $244.99
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  • Supra & Moomba Rear Drain Plug Rear Drain Plug Assembly

    Rear Drain Plug Assembly

    Skiers Choice
    $19.99
    Supra & Moomba Rear Drain Plug Lost your Brass Rear Supra & Moomba Rear Drain Plug?
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    $19.99
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  • Speedometer Pitot Tube

    Speedometer Pitot Tube

    Northern Wholesale
    MSRP: $19.99
    $16.95
    Speedometer Pitot Tube Slotted mounting plate allows for easy installation of this competitive Pitot Tube in the existing holes on your boat. This part will replace your broken Air Guide pitot tube that is no longer available. Best of all this Pitot tube...
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    MSRP: $19.99
    $16.95
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  • 3M 5200 Marine Adhesive Sealant 3oz Tube

    3M 5200 Marine Adhesive Sealant 3oz Tube

    Hannays
    $31.99
    3M 5200 Marine Adhesive Sealant 3oz Tube 3M 5200 Marine Adhesive and Sealant is used when installing new struts or tracking fins. This high strength and white in color. 5200 provides for watertight bonding and sealing of fiberglass and wood. Ideal for...
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    $31.99
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  • MasterCraft OEM Rudder Port - 172 MasterCraft OEM Rudder Port - 172

    MasterCraft OEM Rudder Port - 172

    MasterCraft
    $349.99
    MasterCraft OEM Rudder Port - 172 This genuine MasterCraft OEM Rudder Port is model specific. If you have damaged your rudder Port it is typical that your Rudder is also damaged along with other Under Water Gear. Use the Parts Finder to select your year...
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    $349.99
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  • MasterCraft Nylon T Handle Drain Plug Assembly

    MasterCraft Nylon T Handle Drain Plug Assembly

    MasterCraft
    MSRP: $49.99
    $29.99
    MasterCraft Boats Nylon T Handle Drain Plug Assembly MasterCraft Nylon T handle replacement drain plug. This T handle drain plug is made of Nylon and is made for a marine environment and is a direct factory replacement for MasterCraft boats built from...
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    MSRP: $49.99
    $29.99
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  • Packing Gland Assembly 1 Inch

    Packing Gland Assembly 1 Inch

    $369.99
    Packing Gland For 1" Shaft Replace your boats worn packing gland with this new assembly. Specifically designed for boats with a 1 1/8" drive shaft. Please note this part DOES NOT include log shaft packing, this must be purchased separately This part is...
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    $369.99
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  • Rudder Key 1/4" x 3/4"

    Rudder Key 1/4" x 3/4"

    MSRP: $9.99
    $8.99
    Rudder Key 1/4" x 3/4" Rudder Key 1/4" x 3/4" Replacing your cotter pin is cheap insurance and should never be overlooked. This is too important of a piece to be with out and letŒÍs face it, there is no way to look cool while stranded on the lake. This...
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    MSRP: $9.99
    $8.99
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  • OJ Prop Puller for Inboard Boats

    Universal OJ Prop Puller For Inboard Boats

    OJ Props
    $120.00
    OJ Prop Puller for Inboard Boats Effortless Propeller Removal – Built Tough for Serious Boat Owners The OJ Prop Puller is a must-have tool for any inboard boat owner looking to remove or replace their propeller with ease and confidence. Engineered...
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    $120.00
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  • Rudder Cotter Pin 2" Long | 3/16

    Rudder Cotter Pin 2" Long | 3/16

    OReilly Auto Parts
    MSRP: $2.99
    $2.50
    Rudder Cotter Pin 2" Long | 3/16 The Rudder Cotter Pin is a small but essential part. Replacing your cotter pin is cheap insurance and should never be overlooked. This is too important of a piece to be with out and letŒÍs face it, there is no way to...
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    MSRP: $2.99
    $2.50
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  • MasterCraft OEM Rudder - 176 MasterCraft OEM Rudder - 176

    MasterCraft OEM Rudder - 176

    MasterCraft
    $599.99
    MasterCraft OEM Rudder- 176 This genuine MasterCraft OEM Rudder is model specific. If you have damaged your rudder it is typical that your Rudder Port is also damaged along with other UnderWater Gear. Use the Parts Finder to select your year make and...
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    $599.99
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  • Mastercraft Tracking Fin - 4 Bolt

    Mastercraft Tracking Fin - 4 Bolt

    MasterCraft
    $319.99
    Mastercraft Tracking Fin - 4 Bolt This 4 Bolt Mastercraft Tracking Fin is suited for boats between 1979-2000. If you're unsure whether this tracking fin is for your boat - please call us at 763-404-7372 
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    $319.99
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WaterSkis.com makes it easy to find the exact underwater gear your inboard boat needs—from drive shafts and struts to rudders and more. With parts for Mastercraft, Moomba, Supra, and other leading brands, our Boat Part Lookup Tool helps ensure a perfect fit every time. Looking to complete your repair? Explore propellers or steering components
 for a full performance upgrade.