Small steel fishing boats
FISHING BOAT DESIGNS: 4. SMALL STEEL FISHING BOATS
Prepared by David J. Eyres
Fisheries Technology Service, Fishery industries Division
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS, Rome, 1984
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FAO - Small steel fishing boats
PREPARATION OF THIS PAPER
The paper contains designs of two general purpose steel fishing boats and general guidance on boatbuilding in steel plus cost estimating for fisheries officers, vessel owners and boat builders having experience in working with other materials.
ABSTRACT
This, the fourth of the FAO fishing boat design handbooks, deals with the subject of small steel fishing boats.
The publication is intended to serve individuals and companies with experience of structural steel fabrication, boat- builders working with other materials who may wish to build larger craft in steel, and finally fisheries officers and vessel owners who require guidance on boatbuilding in this material.
Section 2 describes the material, the building site and tools required, fabrication and outfitting of steel boats.
Section 3 contains information on protection against corrosion and Section 4 presents a simple method of cost estimating to construct a small steel craft.
The handbook also contains designs of 15 m and 21 m general purpose steel fishing boats. These consist of general arrangements, lines and hull construction drawings, steel quantities and outline specifications.
ABSTRACT
This, the fourth of the FAO fishing boat design handbooks, deals with the subject of small steel fishing boats.
The publication is intended to serve individuals and companies with experience of structural steel fabrication, boat- builders working with other materials who may wish to build larger craft in steel, and finally fisheries officers and vessel owners who require guidance on boatbuilding in this material.
Section 2 describes the material, the building site and tools required, fabrication and outfitting of steel boats.
Section 3 contains information on protection against corrosion and Section 4 presents a simple method of cost estimating to construct a small steel craft.
The handbook also contains designs of 15 m and 21 m general purpose steel fishing boats. These consist of general arrangements, lines and hull construction drawings, steel quantities and outline specifications.
CONTENTS
- INTRODUCTION
- BUILDING IN STEEL
- PROTECTION AGAINST CORROSION
- COST ESTIMATING
- ANNEX
Outline Specification for 15m and 21m Steel Fishing Boats 16
LIST OF DRAWINGS
- 15m Steel Fishing Boat
- 21m Steel Fishing Boat
- 15m and 21m Steel Fishing Boats
1. INTRODUCTION
This publication in the FAO Fishing Boat Design series deals with the construction of small steel fishing boats. By small steel boats is meant fishing vessels of less than say 30 metres overall length where the required building facilities and equipment are modest and the construction techniques somewhat different from those of larger shipbuilding practice. Generally the construction of boats in steel is not considered below say 12 metres in length where steel is at a weight disadvantage and below 15 metres in the case of tropical marine conditions because of corrosion rates on the thinner steel plate used. The design of two different general purpose steel fishing boats of 15 m and 21 m overall length are presented.
Simple hull forms are utilized to avoid the use of sophisticated equipment and skills and the text provides information on the material and its maintenance, the necessary building equipment and the important principles which differentiate steel boatbuilding from general steel fabrication practices. It is not the intention to teach the basic skills of welding and gas cutting, a knowledge of which is assumed and is not uncommon in developing countries. The purpose of the publication is rather to show how these skills can be adapted to steel boatbuilding. Detailed information on construction techniques is not within the scope of the booklet and the notes are necessarily brief, but an attempt has been made to cover the more important points and the drawings contain a great deal of extra detail to help the inexperienced builder.
For steel hulls of less than 30 m in length, the equipment and building facilities required are modest and can be compared with the traditional wood boatyard rather than the highly automated steel shipyards producing larger vessels.
Notes on estimating steel weights and costs of steel fishing boats are also included. Finally the layouts of the two designs presented are discussed in detail.
The two steel fishing vessel designs may be suitable for various fishing operations within the Exclusive Economic Zones (EEZs) of selected developing countries but should be adapted to local fishing conditions. For practical reasons full working drawings and details of construction could not be included in this paper. The designs comply with the FAO/ILO/IMO Guidelines for the Design, Construction and Equipment of Small Fishing Vessels, published by IMO. Scantlings are in accordance with good practice for this size of craft and should meet the requirements of most regulating authorities. The Organization, however, takes no responsibility that this will be the case and the onus is on the builder to meet his legal responsibilities for plan approval and survey where this is necessary.
It is also recommended that safety precautions specific to steel fabrication, erection and outfitting be followed during the construction of the boats. Guidelines from the ILO publication "Safety and Health in Shipbuilding and Ship Repairing" should be followed.
Simple hull forms are utilized to avoid the use of sophisticated equipment and skills and the text provides information on the material and its maintenance, the necessary building equipment and the important principles which differentiate steel boatbuilding from general steel fabrication practices. It is not the intention to teach the basic skills of welding and gas cutting, a knowledge of which is assumed and is not uncommon in developing countries. The purpose of the publication is rather to show how these skills can be adapted to steel boatbuilding. Detailed information on construction techniques is not within the scope of the booklet and the notes are necessarily brief, but an attempt has been made to cover the more important points and the drawings contain a great deal of extra detail to help the inexperienced builder.
For steel hulls of less than 30 m in length, the equipment and building facilities required are modest and can be compared with the traditional wood boatyard rather than the highly automated steel shipyards producing larger vessels.
Notes on estimating steel weights and costs of steel fishing boats are also included. Finally the layouts of the two designs presented are discussed in detail.
The two steel fishing vessel designs may be suitable for various fishing operations within the Exclusive Economic Zones (EEZs) of selected developing countries but should be adapted to local fishing conditions. For practical reasons full working drawings and details of construction could not be included in this paper. The designs comply with the FAO/ILO/IMO Guidelines for the Design, Construction and Equipment of Small Fishing Vessels, published by IMO. Scantlings are in accordance with good practice for this size of craft and should meet the requirements of most regulating authorities. The Organization, however, takes no responsibility that this will be the case and the onus is on the builder to meet his legal responsibilities for plan approval and survey where this is necessary.
It is also recommended that safety precautions specific to steel fabrication, erection and outfitting be followed during the construction of the boats. Guidelines from the ILO publication "Safety and Health in Shipbuilding and Ship Repairing" should be followed.
OUTLINE SPECIFICATION FOR 15m AND 21m STEEL FISHING BOATS
The two designs illustrated in this handbook represent two quite different arrangements but having hulls which could be utilised with alternative layouts to suit a particular fishery. Basically both boats could be considered multi-purpose although the arrangements shown illustrate deck equipment for one particular type of fishing,
15 m Steel Fishing Boat
The design as presented in Drawing No. SB1-1 is purely for stern trawling and such a design may be utilised for one boat bottom trawling in coastal waters and both bottom and mid-water pair trawling. Where the fishing may be seasonal limiting the bottom trawling to a part of the year then it is useful if the vessel can be utilised without major modification to practice other forms of fishing. In this case using the basic hull design the deck equipment could be re-arranged to allow the vessel to be operated as a combination trawler/purse seiner or as a long liner/gill netter. Utilised solely as a trawler the stern gantry arrangement is preferred to carry the trawl blocks with a direct warp lead from winch and tackle for lifting the cod end over the transom. If the vessel were to be used as a combination trawler/purse seiner, the deck layout should be rearranged to provide a mast and boom for handling both the trawl cod end and the purse seine. Portable trawl davits should also be included so that the davit can be removed from the side on which the purse seine net is to be hauled. The offset wheelhouse is so placed to provide additional working space on the starboard side for either handling the purse seine or for siting a net/line hauler for line and gill net fishing. The hauler should be positioned forward where the helmsman can see the line or net coming aboard and there needs to be adequate room to work around the hauler. For purse seining the purse davit could be arranged on the starboard side with pursing wire leads from the athwartships winch drums to lead blocks at the rear of the house hence to the purse davit. (See FAO Fisheries Technical Paper No. 188, Fishing Boat Designs:3 - Small Trawlers). The house can be arranged on the centreline if the vessel is intended only for stern trawling or offset to starboard if the owner favours fishing from the port side.
The vessel has a large working deck area aft with raised forward deck for protection. An insulated fish hold for stowage of fish on ice is provided. With the insulated hold aft in this type of boat and to utilise fully the space, it will tend to have restricted depth aft and therefore two hatches are fitted to make loading and discharging easier and reduce wastage in warmer climates. Typical fish hatch construction is shown in Drawing No, SB1/2-4. The hold can usefully be subdivided for carrying ice to the grounds and smaller quantities of fish species if so desired. The hold in any case should be fitted with removable and semi-permanent fish hold divisions about 1.5 m apart. Access for inspection and re-packing of the stern gland is provided by a small section of portable insulation at the bottom of the fish hold in way of the shaft. It is preferred that lubrication of the bearing is done remotely from the engine room aft bulkhead area.
Accommodation consists of a wheelhouse with cooking and food storage/preparation facilities adequate for some three to four days at sea. A separate toilet/shower with entrance from the open deck is provided and there is below deck sleeping accommodation with four berths. A sliding door, shown on Drawing No. SB1-11, on the helmsman's side of the wheelhouse, does not interfere with the deck area and permits him to view any fishing operation on the deck in the vicinity of the wheelhouse. A good view of the winch and after working deck area which is a prerequisite of stern trawling operations is also afforded the helmsman by the wheelhouse location and windows at the back of the wheelhouse. The deckhouse construction is shown in Drawing No, SB1-7,
Deck gear consists of a two drum trawl winch with linked spooling equipment necessary for the direct warp lead to the stern gantry. The winch may be hydraulically driven with pump driven from the power take off on the main engine (or auxiliary engine) or can be mechanically driven with chain or belt drive from a pulley on the main engine power take off to a layshaft arrangement. A winch with a pull of 1 1/2 tons at mid drum and drum capacity of 1000 m of 12 mm diameter warp would be suitable for this particular boat. The anchor wire can be handled by the winch as shown on the general arrangement drawing, the wire being stowed on a separate reel. To aid the handling of the cod end and other fishing nets over the transom it is often good practice to fit a steel roller at the transom bulwark top. With a steel boat there is no reason why the upper rail of the transom should not consist of a heavy duty tube as presented in this design which serves the same purpose as a roller without its disadvantages. Maintenance of rollers and the snagging of nets at its support bearings are particularly troublesome. If purse seining operations are undertaken from the one side it is very important to ensure that the bulwarks on this side and transom are free of protuberances and sharp corners which can snag and tear nets. The stern gantry is arranged with the uppermost cross member supporting the cod end hoisting tackle inboard of the transom so that the cod end swings into the deck area for discharging when lifted above the transom. Retractable arms carrying the eyes for the trawl blocks are fitted to allow these to be stowed inboard of the belting line and the stern gantry carries a 1/2 ton SWL derrick for handling catches alongside or lifting gear. Provision can be made for adjusting the height of the trawl block for clearance of different trawl door sizes.
An economical heavy duty marine diesel engine has been shown in the design drawings but alternative main engines may be fitted in accordance with the owners and builders preference and availability. The Yanmar 6KD CGC.'E engine shown has a continuous rating of 165 hp at 1450 rpm and with a 3.55 to 1 reduction gearbox and 42" (1070 mm) diameter propeller in the nozzle gives an estimated thrust at 4 knots towing speed of almost 2.5 tons. With the nozzle installation in this boat a trawl of similar size to that for an installed power of 210-230 hp without nozzle can be handled with savings in investment and running costs.
Three tons of concrete ballast equally distributed fore and aft as shown in the General Arrangement plan is poured in the void spaces between floors after coating the steelwork with a bitumous paint. This seals these inaccessible areas and improves the vessels stability characteristics.
The rudder, stock and tube details are shown in Drawing SB1-10.
21 m Steel Fishing Boat
The arrangement for this vessel features accommodation and engine aft with a dry fish hold and three fish tanks forward as shown in Drawings Nos. SB2 - 1 and SB2-2. This type of arrangement is preferred in various areas for purse-seining and other types of fishing particularly in more exposed waters. The purse winch is located in the shelter of the forecastle and has adequate lead lengths to the purse davit located opposite on the starboard side well forward of amidships to aid maneuvering when pursing and handling the net. Operations are easily observed from the bridge. A maximum clear working deck area is achieved in the forward part of the ship and the forecastle could be extended further aft on the port side to protect the winch and fish handling area from the sun or inclement weather if so desired. The open spaces at the sides of the deck-house particularly on the starboard side and aft deck permit handling and stowage aft of the purse net. An after derrick boom stepped on the deckhouse top carries a purse block which is usually hydraulically driven to assist with net handling.
If so desired the boat may work as a stern trawler with suitable leads from the warp drums to blocks outboard then led aft to trawl blocks carried on arms built into the aft corners of the bridge deck. Positioning of the winch would have to be carefully considered to give the correct leads for trawling and purse seining if such a combination vessel is required. Also the vessel could be arranged for long lining with the line hauler mounted forward in the shelter of the forecastle.
The vessel as designed has three chilled sea water tanks and an ice hold. Alternative arrangements for the fish stowage space could be utilised to suit the owners preference. For the purse seining operation fish stowed in the chilled sea water tanks (50-60 percent of fish to 20-25 percent of sea water and 20-25 percent of ice) will maintain good quality. This is particularly important if food fish is to be the end product and it reduces the handling problem where large quantities of fish are required to be iced and stowed without crushing. Chilled sea water (CSW) as opposed to refrigerated sea water is proposed on the assumption that the time taken between taking on sea water after leaving port and beginning to stow the catch is insufficient to permit lowering the sea water temperature to the level required. This can be a problem particularly in areas where the initial sea water temperature is high and the fishing grounds not too distant from the point of loading. A refrigerated system could be installed for these tanks if the cost is justified and the system desired by the owner, the pump, valves and refrigeration plant being located in the engine room. A pump with sea suction and overboard discharge only is required for the chilled water system to fill and empty the tanks. Suctions from the tanks are fitted with strainers to prevent the size of fish caught being taken into the pump. Ice and bulk or boxed fish can be carried in the dry hold which is arranged with fish ponds. Usually compressed air is supplied to the CSW tanks to improve the cooling facilities.
Aft of the engine room there is a net and gear stowage space with hatch access from the main deck. This is to be lined out with timber sparring to suit the stowage requirements.
The forward mast carries a 1 ton SWL derrick which can be used for brailing and discharging iced fish. It could also be used to support a temporary canvas or similar awning over the foredeck if this was considered necessary. Forward of the dry fish hold bulkhead a void space aft of the fuel tank is provided for fitting an echosounder sonar transducer if required.
Accommodation consists of two deck cabins in the forecastle with up to four bunks in each. Deck cabins are preferred to below deck spaces for tropical conditions. The elevated wheelhouse has a clear view of the forward working deck and incorporates accommodation which could be occupied by the master if this is local practice. Windows in the after bulkheads and doors of this structure should be arranged to afford the helmsman a reasonable view aft particularly if trawling operations are planned. The main deckhouse contains a two berth cabin, mess and galley space for extended voyages and W/C and shower for the crew. The construction of the deckhouse is shown in Drawing No. SB2-7.
The engine shown is a Yanmar 6M-TE with continuous rating of 300 bhp at 750 rpm and a 2 to 1 reduction gearbox giving the vessel an estimated free running speed of 9.5 knots. If the vessel was to be used for trawling it is recommended that a nozzle and appropriate propeller is fitted.
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15 m Steel Fishing Boat
The design as presented in Drawing No. SB1-1 is purely for stern trawling and such a design may be utilised for one boat bottom trawling in coastal waters and both bottom and mid-water pair trawling. Where the fishing may be seasonal limiting the bottom trawling to a part of the year then it is useful if the vessel can be utilised without major modification to practice other forms of fishing. In this case using the basic hull design the deck equipment could be re-arranged to allow the vessel to be operated as a combination trawler/purse seiner or as a long liner/gill netter. Utilised solely as a trawler the stern gantry arrangement is preferred to carry the trawl blocks with a direct warp lead from winch and tackle for lifting the cod end over the transom. If the vessel were to be used as a combination trawler/purse seiner, the deck layout should be rearranged to provide a mast and boom for handling both the trawl cod end and the purse seine. Portable trawl davits should also be included so that the davit can be removed from the side on which the purse seine net is to be hauled. The offset wheelhouse is so placed to provide additional working space on the starboard side for either handling the purse seine or for siting a net/line hauler for line and gill net fishing. The hauler should be positioned forward where the helmsman can see the line or net coming aboard and there needs to be adequate room to work around the hauler. For purse seining the purse davit could be arranged on the starboard side with pursing wire leads from the athwartships winch drums to lead blocks at the rear of the house hence to the purse davit. (See FAO Fisheries Technical Paper No. 188, Fishing Boat Designs:3 - Small Trawlers). The house can be arranged on the centreline if the vessel is intended only for stern trawling or offset to starboard if the owner favours fishing from the port side.
The vessel has a large working deck area aft with raised forward deck for protection. An insulated fish hold for stowage of fish on ice is provided. With the insulated hold aft in this type of boat and to utilise fully the space, it will tend to have restricted depth aft and therefore two hatches are fitted to make loading and discharging easier and reduce wastage in warmer climates. Typical fish hatch construction is shown in Drawing No, SB1/2-4. The hold can usefully be subdivided for carrying ice to the grounds and smaller quantities of fish species if so desired. The hold in any case should be fitted with removable and semi-permanent fish hold divisions about 1.5 m apart. Access for inspection and re-packing of the stern gland is provided by a small section of portable insulation at the bottom of the fish hold in way of the shaft. It is preferred that lubrication of the bearing is done remotely from the engine room aft bulkhead area.
Accommodation consists of a wheelhouse with cooking and food storage/preparation facilities adequate for some three to four days at sea. A separate toilet/shower with entrance from the open deck is provided and there is below deck sleeping accommodation with four berths. A sliding door, shown on Drawing No. SB1-11, on the helmsman's side of the wheelhouse, does not interfere with the deck area and permits him to view any fishing operation on the deck in the vicinity of the wheelhouse. A good view of the winch and after working deck area which is a prerequisite of stern trawling operations is also afforded the helmsman by the wheelhouse location and windows at the back of the wheelhouse. The deckhouse construction is shown in Drawing No, SB1-7,
Deck gear consists of a two drum trawl winch with linked spooling equipment necessary for the direct warp lead to the stern gantry. The winch may be hydraulically driven with pump driven from the power take off on the main engine (or auxiliary engine) or can be mechanically driven with chain or belt drive from a pulley on the main engine power take off to a layshaft arrangement. A winch with a pull of 1 1/2 tons at mid drum and drum capacity of 1000 m of 12 mm diameter warp would be suitable for this particular boat. The anchor wire can be handled by the winch as shown on the general arrangement drawing, the wire being stowed on a separate reel. To aid the handling of the cod end and other fishing nets over the transom it is often good practice to fit a steel roller at the transom bulwark top. With a steel boat there is no reason why the upper rail of the transom should not consist of a heavy duty tube as presented in this design which serves the same purpose as a roller without its disadvantages. Maintenance of rollers and the snagging of nets at its support bearings are particularly troublesome. If purse seining operations are undertaken from the one side it is very important to ensure that the bulwarks on this side and transom are free of protuberances and sharp corners which can snag and tear nets. The stern gantry is arranged with the uppermost cross member supporting the cod end hoisting tackle inboard of the transom so that the cod end swings into the deck area for discharging when lifted above the transom. Retractable arms carrying the eyes for the trawl blocks are fitted to allow these to be stowed inboard of the belting line and the stern gantry carries a 1/2 ton SWL derrick for handling catches alongside or lifting gear. Provision can be made for adjusting the height of the trawl block for clearance of different trawl door sizes.
An economical heavy duty marine diesel engine has been shown in the design drawings but alternative main engines may be fitted in accordance with the owners and builders preference and availability. The Yanmar 6KD CGC.'E engine shown has a continuous rating of 165 hp at 1450 rpm and with a 3.55 to 1 reduction gearbox and 42" (1070 mm) diameter propeller in the nozzle gives an estimated thrust at 4 knots towing speed of almost 2.5 tons. With the nozzle installation in this boat a trawl of similar size to that for an installed power of 210-230 hp without nozzle can be handled with savings in investment and running costs.
Three tons of concrete ballast equally distributed fore and aft as shown in the General Arrangement plan is poured in the void spaces between floors after coating the steelwork with a bitumous paint. This seals these inaccessible areas and improves the vessels stability characteristics.
The rudder, stock and tube details are shown in Drawing SB1-10.
21 m Steel Fishing Boat
The arrangement for this vessel features accommodation and engine aft with a dry fish hold and three fish tanks forward as shown in Drawings Nos. SB2 - 1 and SB2-2. This type of arrangement is preferred in various areas for purse-seining and other types of fishing particularly in more exposed waters. The purse winch is located in the shelter of the forecastle and has adequate lead lengths to the purse davit located opposite on the starboard side well forward of amidships to aid maneuvering when pursing and handling the net. Operations are easily observed from the bridge. A maximum clear working deck area is achieved in the forward part of the ship and the forecastle could be extended further aft on the port side to protect the winch and fish handling area from the sun or inclement weather if so desired. The open spaces at the sides of the deck-house particularly on the starboard side and aft deck permit handling and stowage aft of the purse net. An after derrick boom stepped on the deckhouse top carries a purse block which is usually hydraulically driven to assist with net handling.
If so desired the boat may work as a stern trawler with suitable leads from the warp drums to blocks outboard then led aft to trawl blocks carried on arms built into the aft corners of the bridge deck. Positioning of the winch would have to be carefully considered to give the correct leads for trawling and purse seining if such a combination vessel is required. Also the vessel could be arranged for long lining with the line hauler mounted forward in the shelter of the forecastle.
The vessel as designed has three chilled sea water tanks and an ice hold. Alternative arrangements for the fish stowage space could be utilised to suit the owners preference. For the purse seining operation fish stowed in the chilled sea water tanks (50-60 percent of fish to 20-25 percent of sea water and 20-25 percent of ice) will maintain good quality. This is particularly important if food fish is to be the end product and it reduces the handling problem where large quantities of fish are required to be iced and stowed without crushing. Chilled sea water (CSW) as opposed to refrigerated sea water is proposed on the assumption that the time taken between taking on sea water after leaving port and beginning to stow the catch is insufficient to permit lowering the sea water temperature to the level required. This can be a problem particularly in areas where the initial sea water temperature is high and the fishing grounds not too distant from the point of loading. A refrigerated system could be installed for these tanks if the cost is justified and the system desired by the owner, the pump, valves and refrigeration plant being located in the engine room. A pump with sea suction and overboard discharge only is required for the chilled water system to fill and empty the tanks. Suctions from the tanks are fitted with strainers to prevent the size of fish caught being taken into the pump. Ice and bulk or boxed fish can be carried in the dry hold which is arranged with fish ponds. Usually compressed air is supplied to the CSW tanks to improve the cooling facilities.
Aft of the engine room there is a net and gear stowage space with hatch access from the main deck. This is to be lined out with timber sparring to suit the stowage requirements.
The forward mast carries a 1 ton SWL derrick which can be used for brailing and discharging iced fish. It could also be used to support a temporary canvas or similar awning over the foredeck if this was considered necessary. Forward of the dry fish hold bulkhead a void space aft of the fuel tank is provided for fitting an echosounder sonar transducer if required.
Accommodation consists of two deck cabins in the forecastle with up to four bunks in each. Deck cabins are preferred to below deck spaces for tropical conditions. The elevated wheelhouse has a clear view of the forward working deck and incorporates accommodation which could be occupied by the master if this is local practice. Windows in the after bulkheads and doors of this structure should be arranged to afford the helmsman a reasonable view aft particularly if trawling operations are planned. The main deckhouse contains a two berth cabin, mess and galley space for extended voyages and W/C and shower for the crew. The construction of the deckhouse is shown in Drawing No. SB2-7.
The engine shown is a Yanmar 6M-TE with continuous rating of 300 bhp at 750 rpm and a 2 to 1 reduction gearbox giving the vessel an estimated free running speed of 9.5 knots. If the vessel was to be used for trawling it is recommended that a nozzle and appropriate propeller is fitted.
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FAO - Small steel fishing boats
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