Design and Construction
Castro's 1720 is a fractional-sloop monohull of 8.0 m overall and 2.5 m beam, with a solid fiberglass hull laid up from stitched and woven glass reinforcements hull lay-up uses stitched and woven glass reinforcements laminated in Vinylester resin. The deck carries a balsa core, and the solid laminate below is expected to stay tough and durable thanks to the resin choice. Righting moment comes from a 630 kg lead bulb keel, a substantial fraction of the 1,200–1,250 kg displacement, and the boat's ballast-to-displacement character gives it the kind of stability a one-design racer needs when pressed. She is no lightweight, yet the lead in the keel means plenty of righting moment for the rig carried above.
Rig and Handling
Upwind the 1720 shows 42 sq m of sail area, big for the boat's length, with a choice of two jibs — both sheeted to a single track through a two-to-one sheet and ratchet turning block — and a couple of deep reefs to regulate power choice of two jibs and a couple of deep reefs allows regulation of the power upwind. A substantial mainsail gives power even in light air, but the boat must be sailed flat; as soon as she heels, the mainsheet or traveller has to be eased or a mild broach follows, and constant easing of sheets is needed at heel to prevent a broach, though recovery is fast. Downwind, the immense 68 sq m asymmetric spinnaker forces a deep angle that keeps her out of the high-performance planing envelope in moderate air, and she was relatively slow to accelerate and reluctant to plane then. In more breeze the hull form will get up and plane, and later reports credit her with rapid downwind pace in a blow. The smaller short-hoist spinnaker proved a better medium-air bet, nearly matching drive with less heeling moment.
Accommodations
This is virtually a day boat. The open cockpit holds four or five, but below decks there is only cramped storage space — an estate agent would not call it accommodation. The space is essentially empty and awkward to enter; it can stow spinnakers and warps, but getting a mainsail in and out is hard. The short deck-level guard rails keep crew from sitting facing outward and limit hiking, and foot braces hold shorter-legged crew when upright yet not at large or extreme angles of heel.
Known Issues
The deck layout makes it nearly impossible to work the boat with the hatch open, avoiding J24-style swamping but complicating access. Testers found the haphazard positioning of deck fittings a major obstacle to enjoyment, and around the mast base the control lines and halyards led to almost the same spot with little logic, crowding the working area. The mainsheet and backstay cleats were hard to operate from the rail and needed a firm foot shove; the backstay itself seemed to need a fundamental rethink to be effective. The vast stowage bin either side of the winch pod launches the kite simply but has no top, so the spinnaker can cascade over the side on takedown — canvas flaps and elastic would fix it.
Refits and Ownership
Ownership centres on a one-design racer sailed by four or five ordinary sailors without terror or boredom, demanding a fit mainsheet trimmer because of the big sail area and flat-sailing need. The bin fix is minor canvas work; otherwise the class stays a controlled spec boat meant to deliver affordable competitive racing. With around a hundred on the water by the review and a strong Cork Week fleet, the design fulfilled its market.
The Verdict
The 1720 is a purposeful Irish one-design that trades outright screamer performance for handling ease in club racing, built solidly in Vinylester with a lead keel and a big but manageable rig. She rewards a flat-sailing crew and punishes sloppy heel with broach tendency, yet recovers quickly and planes in breeze. Below decks is day-boat sparse, and deck-gear logic is rough, but the concept — cheap, safe, exciting keelboat racing — is intact.
Pros
- Lead bulb keel and Vinylester solid hull give durability and righting moment
- Substantial mainsail and twin-jib setup power her in light air and upwind
- Planes downwind in stronger breeze with rapid pace reported
- Sails well with four or five ordinary crew without scaring or boring them
Cons
- Must be sailed flat; heels toward broach without constant sheet easing
- Deck fittings and mast-base controls laid out illogically, hard to operate from rail
- No real accommodation; below decks cramped and hard to access
- Spinnaker bin open-topped; spinnaker can go over side on takedown
