Backpack 38 - Tropical cruising catamaran

Sorry, this design is no longer available.
We keep it on the site only as an example of our work.

Backpack 38 sail plan


Affordable cruising in the tropics

~ Plywood or GRP construction

~ Seaworthy Polynesian catamaran

~ Demountable for transport

~ Thin water tropical cruising




Credit Card

Boat Sites


This one was commissioned as my version of the renowned "Wharram" cat concept, intended to bring boating back to affordable basics. I am not ashamed to say that it only came my because James Wharram was not able to do a design for my client at the time. It does not fall within the range of concepts for which I normally design but the type has strong merits so I accepted the commission.

She is not intended as a high performance multihull and must not be compared with other catamarans on that basis. Instead, she was drawn to be a boat of minimum complexity and hassle while giving maximum enjoyment for investment.

Backpack 38 side view

She was originally commissioned as a GRP design for construction on a semi-production basis, for owner completion. Emphasis was on low-tech construction, using single skin GRP with "Coremat" incorporated into the flat panels for stiffening. The new company which was to be set up to build the boats didn't get off the ground so the moulds were never built. Plans for plywood construction have also been drawn for amateur builders, the bridgedeck and rudders still needing to be detailed at this stage.

She is fully demountable for ease of movement from one location to another. The beams are lashed or bolted to the decks and the bridgedeck is constructed in two sections and bolted to the adjacent beams. The slatted foredeck is glued up into a one-piece structure and also fastened to the adjacent beams and the bow netting is lashed to beams and hulls.

Backpack 38 accommodation

Down below there is comfortable but basic accommodation. The starboard hull contains a large double cabin, nav station and head/shower compartment. The port hull houses the saloon and galley. The saloon has a dinette to seat 5, convertible to a large double berth. The galley is basic but quite large, with stove, sinks and extensive work space.

Both hulls feature a forecabin with large single (or cosy double for very good friends). Access is through hatches in the foredecks so alternative access is provided via doors in the bulkheads aft of the forecabins, for use in bad weather. Both hulls also have lazarettes in the sterns, accessible from the aftdecks.

The bridgedeck is divided into two cockpits, each with stowage compartments under the seats. The aft cockpit is the working cockpit, from which steering and sheet handling is done. The forward cockpit is for relaxation and can be covered by a folding tent or fixed dodger to turn it into a cabin with two convertible double berths.

Backpack 38 longitudinal sections

The rig is a low aspect and lightly loaded arrangement, using aluminium tubes or hollow wooden masts set in tabernacles. Individually stayed, the unlikely loss of one mast does not destroy the other. Of identical detailing, the mainmast can be moved forward in the event of loss of the foremast. The headsail can be set on hanks or a roller furler. The foresail and mainsail are gaff headed and use traditional gaff detailing with lashings to masts and gaffs to keep costs down. Control of the foot is by means of a self-vanging wishbone boom sheeted on centreline.

The hulls have a sprayrail full length for dryness and to increase buoyancy and interior volume high up. It also forms a landing off which the berths and dinette seats are built. Below the water she has shallow keels which, along with her fine V-shaped bows, provide windward ability. The rudders have full skegs for grounding protection. Powering is by means of outboards hung on pods below the bridgedeck and lowered by block and tackle.

Backpack 38 section

The BACKPACK 38 is well suited to shallow water cruising, particularly inter-island. Her open bridgedeck nature means that she should keep to the tropics and not head into the colder latitudes where more protection would be needed.,

Follow this link to a list of drawings for this design.


LOA 11,60m [38'1"]

LWL 10,40m [34'1"]

Beam overall 6,50m [21'4"]

Hull beam 1,60m [5'3"]

Draft 0,85m [2'9"]

Displacement 4000kg [8816lb]


Mainsail 23,58sq.m [254sq.ft]

Foresail 20,95sq.m [226sq.ft]

Genoa 19,12sq.m [206sq.ft]




Click here to contact us by whatever method suits you.

This page was updated 6 August 2002

Web design by Dix Design