Seastream 34 — Information, Review, Specs

Ian Anderson·1978·Seastream Yachts Ltd.
Seastream 34 drawingBuilder drawing
Hull type
Monohull · fin
Rig
Ketch
LOA
34' · 10.36 m
Displ.
15,000 lbs · 6,804 kg
First year
1978

The Seastream 34, designed by the prolific Ian Anderson and primarily constructed by Rank Marine, represents a seminal entry in the British deck saloon market. Launched in the late 1970s, the design was a response to the growing demand for a vessel that combined the interior visibility of a motorsailer with the seakindliness and windward performance of a dedicated bluewater cruiser. Built to a high standard of scantlings, the Seastream 34 is characterized by its heavy displacement and robust GRP construction, making it a staple in the secondhand market for sailors eyeing highlatitude voyages or comfortable yearround coastal cruising.

Measurements

Dimensions 01

LOA
34 ft
LWL
27.25 ft
Beam
11 ft
Draft
6.23 ft
Max headroom
-
Air draft
-

Construction & hull 02

Construction
Fiberglass
Hull type
Monohull
Keel type
Fin
Rudder
1× Skeg-Hung
Ballast
6000 lbs
Displacement
15000 lbs
Water
92 gal
Fuel
40 gal

Rig & sails 03

Rig type
Ketch
P · main luff
-
E · main foot
-
I · fore ht.
-
J · fore base
-
Forestay (est)
-
Sail area
-

Calculations 04

SA/D ratio
Ballast/Disp.
40
D/L ratio
330.94
Comfort ratio
32.48
Capsize screening
1.78
Hull speed
7 kn

Sailing Performance & Handling

The Seastream 34 is defined by its substantial displacement and a relatively high ballast ratio, which contributes to a stiff and predictable motion in a seaway. According to editorial assessments by Yachting Monthly, the vessel is not a light-airs performer; its wetted surface area and heavy hull require a decent breeze to come alive. However, once established on a reach, the boat exhibits excellent tracking thanks to its long fin keel and substantial skeg-mounted rudder.

The high freeboard and deckhouse profile do present a significant amount of windage, which can make close-quarters maneuvering under power challenging in a crosswind. Nevertheless, the boat’s ability to carry sail late into a building breeze makes it a "dry" boat in conditions that would see smaller-volume cockpits drenched. Most models were sloop-rigged, though a small number of ketch rigs were produced for those seeking more versatile sail-handling options for short-handed cruising.

Interior Comfort & Variations

The defining feature of the Seastream 34 is its raised deck saloon, which provides 360-degree visibility from the dinette—a luxury rarely found in 34-footers of its era. This layout allows for a secondary internal steering station or a dedicated navigation nook where the watch-keeper can remain warm and dry while maintaining a lookout. The interior joinery is typically heavy teak or mahogany, reflecting the premium positioning of the boat when it was new.

The standard layout features a V-berth in the forecabin, a linear or U-shaped galley located at a lower level to port, and a heads compartment to starboard. A significant variation exists in the aft section: while some hulls feature an aft cabin with a separate entrance from the cockpit, others utilized a walkthrough from the main saloon. The Seastream 34 was eventually succeeded and complemented by the larger Seastream 43, which utilized the same design philosophy but offered significantly more volume for a three-cabin layout. While the 34 does not have "sibling" models built on the exact same hull, it shares a strong familial design language with the Anderson-designed Seastream 43 and 46, which are essentially scaled-up versions of the 34's successful deck saloon blueprint.

Known Issues & Buyer’s Checklist

Prospective buyers should approach the Seastream 34 with a focus on its structural longevity and the specific complexities of its deck saloon design.

  • Window Seals and Frames: The large panoramic windows are a primary failure point. Over decades, the seals can perish, leading to leaks that damage the interior woodwork and headlining. Inspect for water staining around the window sills and behind the saloon seating.
  • Deck Core Integrity: Like many boats of this era, the Seastream 34 uses a balsa-cored deck. While the hull is solid GRP, the deck can suffer from delamination if moisture has penetrated through improperly bedded deck hardware or stanchion bases.
  • Engine Access and Maintenance: Many units were fitted with the original Perkins or Bukh diesel engines. While these are "bulletproof" units, the access under the saloon sole can be cramped for major overhauls. Check the condition of the fuel tanks, as original mild-steel tanks may be reaching the end of their service life.
  • Osmosis: While Ian Anderson designs are known for their heavy lay-ups, hulls from the late 70s and early 80s are susceptible to osmotic blistering. A moisture meter reading and a visual inspection of the gelcoat below the waterline are essential.

Community & Resources

The Seastream brand benefits from a dedicated following among British and European cruisers. The Seastream Owners Association remains the primary technical resource, providing historical brochures and maintenance logs for the 34, 43, and 46 models. Owners often coordinate through specialized cruising forums, sharing specific modifications for the internal steering systems and window replacements.

The Verdict

The Seastream 34 is an overbuilt, honest cruiser that prioritizes safety and crew comfort over outright speed. It is an ideal choice for a couple looking to extend their sailing season into the shoulder months or for those transitioning from a traditional "sailing-in-a-hole" layout to a more airy, light-filled interior.

Pros:

  • Exceptional 360-degree visibility from the saloon.
  • Heavy-duty construction capable of serious offshore work.
  • Internal helm/navigation station for foul-weather protection.

Cons:

  • High windage can make berthing difficult in a blow.
  • Not a competitive performer in light winds or on a race course.
  • Maintenance of large deckhouse windows can be costly.

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