Design and Construction
Ibold's 35-foot hull carries a length-to-beam ratio of 2.87 and a displacement-length ratio of 439, a figure that places it among what reviewers term ultra heavy cruisers anchor. The boat's 41 percent ballast ratio and 1.66 capsize screening value speak to a form meant for offshore steadiness rather than speed around the buoys. With roughly 322 square feet of wetted surface and a long keel, the Endurance 35 is a volume-laden, deeply laden vessel: its immersion rate of about 1,020 pounds per inch means it sits heavily and moves slowly in the water, and the theoretical maximum speed of a displacement hull this long is 6.9 knots. The hull itself is fiberglass.
Rig and Handling
The Endurance 35 is rigged as a ketch, and the standing and running gear dimensions recorded for the design show a workmanlike offshore inventory. Jib and genoa sheets run 31.5 feet at a half-inch diameter, the mainsheet is a lengthy 78.7 feet also at half-inch, and the spinnaker sheets are 69.3 feet on the same diameter anchor. Those long sheet lengths reflect the ketch's divided sail plan and the need to trim from a central cockpit over a long deck. Draft runs about five feet dependent on load, which lets the boat enter most marinas despite its heavy build. The Motion Comfort Ratio of 41.7 quantifies the easy motion that the heavy displacement and long waterline confer in a seaway.
Accommodations
The design was plainly intended for extended passages under both sail and power, carrying 185 gallons of water and 71 gallons of diesel. The beam of 11 feet and long-keel hull form provide the internal volume such a cruising brief demands.
Known Issues
The only cautions implicit in the record are inherent to its type: the ultra-heavy displacement and high immersion rate mean the hull responds sluggishly to sail trim and demands a patient hand, and the long keel limits maneuverability in tight marinas compared with fin-keel contemporaries. These are characteristics of the category, not defects of workmanship.
Refits and Ownership
Ownership means living with a boat built at several yards under Ibold's design, so individual hulls vary in construction detail depending on where and when they were finished. The few hundred built include Belliure's Spanish production and other yards' output. A buyer or owner should expect period-appropriate systems and the refit burden of a fifty-year-old motorsailer rather than any single documented weakness.
The Verdict
The Endurance 35 is a thoroughly traditional heavy-displacement motorsailer ketch, designed by Peter Ibold and built in fiberglass with a long keel. Its numbers — a 439 displacement-length ratio, 41 percent ballast ratio, and 41.7 comfort ratio — describe a boat built for stable, slow, comfortable cruising rather than performance.
Pros
- Ultra-heavy-displacement hull with a 41.7 Motion Comfort Ratio for easy seaway motion
- Long keel and ~5-foot draft allow marina access despite the heavy build
- Ketch rig with generous sheet lengths suited to offshore trim
Cons
- 439 DL-ratio and high immersion rate make for sluggish response and low speed
- Long keel reduces close-quarters maneuverability versus fin-keel boats
- Multiple build yards mean inconsistent per-hull completion
