Hydraulic Equipment List

Anchor winch 12 gpm @ 1,500 psi

Auto Crane, deck crane 6 gpm @ 2,350 psi


9 – Sail Winches

AC Generator

4″ Water Pump

Air Compressor

2.32CuIn Hydraulic Clutch Pump

Hydraulic Power Units

Main Engine Clutch Pump

The 200HP Cummins 5.9, 6BT main engine (on-hand) will provide power for a Northern Tool; High Pressure Hydraulic Clutch Pump, 2.32Cu In, Maximum pressure 3000. 1 1/4in. NPTF inlet, 1in. NPTF outlet. 29.1 @ 3000 and 11.6 GPM @ 1200 RPM, about $520  It has a 2 groove, 7in. pulley that uses type A 1/2in. belts and rotates clockwise (on-hand)

Auxiliary Engine

A 140HP Cummings 3.9, 4BT 3.9 auxiliary engine will power a hydraulic pump and serve as the primary HPU.   The Cummings 6BT and 4BT have exchangeable parts which will reduce required spares and down time.  The hydraulic pump will be capable of producing more than 35 GPM @ 2,000 PSI

12v DC Pump

A 12v DC pump is required for the sail winches and operation of the rudder by an autopilot.

Portable HPU

A portable 10 HP diesel powered HPU with a pump to provide 5-6 GPM at 3,000 PSI will be on board that can be transported by tender for use in powering various hydraulic tools such as water pumps and cutters.   This HPU can alternatively be used for an emergency supply while on-board.

10hp Chinese Yanmar knock-off

The following formula calculates the HP of a pump:
( Pressure * Gallons per Minute ) / 1719 = Pump Horse Power

So to reach our Northern Tool clutch pump’s maximum 11.6gpm at 3000 psi we need: (3000 * 11.6) / 1719 = 20.24 HP. But the deck crane only needs 6 GPM at 2,350 PSI so if there were no losses then (2350 * 6) / 1719 = 8.2 HP would be sufficient. So if the anchor winch can operate satisfactorily with 6 GPM at 2,350 PSI then counting for some efficiency losses, a 10 HP engine is needed.

We got a 10hp Chinese diesel engine off eBay for $580. Another option will be a 13.4hp, water cooled Yanmar; www.surpluscenter.com has them for $1000.

Our 10hp, 418 cc, Chinese diesel is a 4 stroke and 10 HP at 3600 RPM. And 8.6 HP at 3000 RPM. It has a 1″ shaft with a 1/4″ key. The shaft turns counter-clockwise, like most small engines. A direct drive a pump then needs to work in the clockwise direction.

Horse Power / Gallons per Minute * 1719 = Pressure

Division of Systems

In order to simplify the overall system and limit the impact of any one failure, the hydraulic system will be divided into sub-systems.

  1. Anchor Winch
  2. Sail Winches
  3. Deck Crane
  4. Rudder /  Autopilot
  5. Auxiliary Equipment:
    • AC Generator
    • Trash Pump
    • Air Compressor

1. Anchor Winch

Anchor WinchThe anchor winch is a converted White truck winch that was powered by a PTO.  It’s now direct driven from a hydraulic motor.  The smallest HPU we will use would be the 10hp diesel engine providing 11.6 gpm @ 1,247psi  and the next HPU would be the clutch pump on the main engine: 29.1 gpm @ 3000psi.

We want the winch line speed to be about 50 ft per minute on the first wraps, and it can be upwards to 350 ft/min on the final wraps. The smaller 6″ wide side of our winch has the most change from the first wraps to the last.

The calculation is (3.14pi *8.75 drum diameter) / 12in = 2.8 ft/revolution. 50 ft requires 50/2.8=17.8 revolutions. The worm gear reduction on the winch is 29:1, so 18 revolutions of the drum requires 18 * 29 = 522 revolutions on the motor. So we want a motor that does around 522 rpm with 11.6gpm from the 10 hp HPU.  When running it with the main engine it will be capable of much higher speed.

Hydraulic motors are categorized by their displacement. For example an 8 cubic inch displacement motor uses 8 cubic inches of fluid per revolution. So: Gallons per minute * 231 cubic inches per gallon / motor displacement cubic inches = motor rpm.

At 11.6 gpm an 8 cubic in motor is: 11.6 * 231 / 8 = 334 rpm. And at 29.1 gmp it’s 29.1 * 231 / 8 = 840 rpm

So if we want 522 rpm with 11.6 gpm then: (Gallons per minute * 231 cubic inches per gallon ) /motor rpm = displacement. Or (11.6 * 231) / 522 = 5.13 cubic inches. If we flowed 29.1 gpm to the motor it would spin at 29.1 * 231 / 5 = 1344 rpm which is way above the maximum rpm for most 5 cubic inch motors which is around 900 rpm.

The torque required by the winch varies greatly.  The motor will provide approximately 2000 in-lbs, less 15 inches for the drum, times 29 for the worm gear reduction,  less about 20% for loses and the pull on the line will be approximately:  2000/15*29*.8= 3093 pounds.

Anchor Winch Motor and Control Valve

Anchor Winch Hydraulic Motor

5.9 cu. in, 1840 psi, 15.8 gpm, 1425 in-lbs, 1/2″ ports

The motor is 5.9 cubic inch displacement so with the 11.6gpm the line speed should be: ((pump gpm * 231 / cu in displacement) / gear reduction) * ft per rotation = line ft per minute or (((11.6*231)/5.9)/29)*2.8=43.8 ft/minute

The anchor winch control has to be at the winch and installed with a linkage that allows it to be operated from either side of the winch so it can be operated when working with either capstan.  A spool valve makes sense here, but it would also be nice to have a control at the helm too that would make it easier to operate the boat single handed.

Hydraulic Spool Valve

Single spool, open center, 18 gpm w/ Flow Control 

The valve we selected is more than twice the cost of most single spool valves, but that’s because it comes with a flow control adjustment as well as a relief valve. The flow control will allow us to limit the speed of the motor so that it does not exceed it’s maximum 670 rpm when the hydraulic pump is being powered from the main engine. Addition flow will simply be router past the valve so it will allow us to control the maximum rpm of the spool when the hydraulic pump is being powered by the main engine and capable of too much flow.


2. Sail Winches

Sail Winch V2

Sail Winch V2

Chinese Junks are easier to sail and so easier to automate and we plan to and push button controls for the basic sail handling.  Each of the three mast will have three winches.  One for raising and lowering the sail and two for the lines on each side of the sail that control the sails angle to the wind.

Design Features
1)  Operated on hydraulics from the pilothouse or automatically by a computer that is monitoring heal and wind speed.
2) Optionally operated with hydraulics from the winch by activating the electric hydraulic valve.  Smaller load winches will not need this option.
3) Operated manually without any reliance on hydraulics.
4) Open spool / Capstan so the line can be moved to or from another winch.
5) Able to freewheel so the line can be played out using the brake
6) Mechanical break – not reliant on the hydraulics.
7) Mechanical crank with reduction gear that is not reliant on hydraulics.
8) Designed so that the non-hydraulics components can be cut on a CNC plasma table.
9) Designed to hole a minimum of 40 ft of 3/4″ line on a single layer.

Hydraulic Wheel Motor

12 cu in, reversible, 2000 psi, 3222 in-lb, 288 rpm, 15 gpm, Ports SAE 10



The winch is designed around a hydraulic wheel motor and a disk break hub. The hub can fit inside a 10 inch diameter pipe that would form the spool drum.  A 1000 pound load on the halyard would need 6000 inch pound.  A 12 cu in motor will provided 6300 inch pounds.  The 1.3 gmp pump delivers 300 cubic inches per minute.  So the 12 cu in motor will rotate 300/12= 25 rpm.  A 12 inch diameter pipe will hold over 3 ft per wrap.  A 12 inch wide spool will hold 16 wraps or about 50 feet of 3/4″ giving the total lift time of about 30 seconds.  And double braid dacron has a 1375 foot working load.


Winch Valve Schematic

Winch Valve Schematic

In order to save cost and complexity, the control valves for all of the sail winches will be single gang, located in the engine room with a flexible hydraulic pressure and return line going to each winch location.


3. Deck Crane

Deck Crane

Auto Crain is  based right here in Tulsa, Oklahoma.  With 80 feet of cable on the winch, a lifting capacity of 2,500 pounds at 10 feet, and 1,250 at 20 feet, this crane will give use access over both the port and starboard sides of the boat. We found this on on a 1 ton truck at an auction.  It’s normal HPU is the same 6 gpm, 2,350 psi, electric clutch pump we will mount on our main engine.


4. Rudder / Autopilot

1000 pound Fish Tail Rudder

1000 pound Fish Tail Rudder

Our 40 ton, 65′ water line boat with a 23 square foot rudder will see loads up to 21,000 foot pounds on the rudder post.

The primary steering will be a manual chain and cable system, but hydraulic cylinders will also be attached to the rudder quadrant to allow the boat to be maneuvered with hydraulics from the helm or with a autopilot.  The autopilot controller will be Arduio other DIY controller board driving a proportional directional control valve by varying the current.

Hydraulic cylinder: welded, double acting, 3.5″ bore, 20″ stroke, 1.75″ rod, clevis, 30.25″ retracted, 50.25 extended, SAE 8 port, 28,800 lb column load.  pi * (3.5/2)^2 * 20 * 2 = 385 cu in

It is understood that the autopilot will not be used in rough sea conditions and so the duty cycle will be 25%.  The supply pump is required to be 12 volt.

5. Auxiliary Equipment: AC Generator, Trash Pump, Air Compressor

AC Generator

From diesel engine to hydraulic pump to AC generator to a tool is a long route with a lot of power loss and heat generated along the way, but it is not without it’s benefit. If we were going to run another engine for an air compressor and another for a 4 inch trash pump, and another for hydraulic tool, then we would be maintaining a lot of engines. The advantage comes from having a Cummins 4BT diesel to power multiple pieces of equipment. The 4BT is also shares a number of parts with our larger 6BT engine that drives the prop.

(More Coming Soon)