High speeds are not difficult to attain, but comfort and control at speed requires intelligent design.
Our power boats share a common theme – they are amongst the most capable and seakindly on the water (for their size and speed), a fact we attribute to our sailing design philosophy, which involves designing boats for a variety of conditions, not just flat, calm, sunny days.
Our experience is that whilst a power boat race team will sensibly accept a compromise on comfort to attain higher speeds, a family or group of charter guests will not. In the case of the latter, we often see a small reduction in maximum speed accepted to ensure greater comfort and stability – something that is equally valid in a luxury superyacht tender as it is in a commercial dive boat.

Some of our recent projects include:

Moana 56ft Power Cat
Newsflash - Moana 56 wins 'Best multi-hull motor yacht over 50ft' and nominated for 'Best Asian built yacht' at the Asia Boating awards 2109. Chris Wong and his team have successfully launched the first Moana 56 at the Xinlong Shipyard. Early seatrials indicate she's exceeded the required design speed at full load displacement by a couple of knots. She's beatifuly built to a high standard with a metallic painted exterior and certified under CCS. The canoe-sterned hulls are pushed along by twin Yanmar 6LP 315hp engines turning large diameter, slow reving, big bladed props on a zero degree shaft angle for great efficiency and very quiet running. The chine location, wing-deck and canoe-stern design were the subject of CFD analyses in both calm water and headseas. It has certainly paid off, as Chris Wong remarked during the delivery to Shen Zhen in a seaway, "I have to say, your hull is amazing". That's the sort of feedback we like to hear above and beyond the speed and RPM data.Hulls 02 and 03 are now in the production schedule.

Vision 68
The first Vision 68 was launched in January 2018 at Horizon Yachts' Kaohsiung facility. The exterior by JQB in Seattle is striking, and the overall look of the vessel is very purposeful. The 6m/19'6" beam and long waterline under the plumb bow make for a generous interior volume, and the extra sole width forward offers an arrangement not seen before in this size of vessel. With her slender beam-length ratio and reduced transom immersion for less stern squat at cruising speeds she has the potential for serious long range cruising. The hull was both tank tested and analysed with our in-house CFD to balance reduced drag and low wash at 10-12knot against making 25kn at 50tonnes displacement. Not a straightforward set of criteria. Horizon Yachts, based in Taiwan, are the world’s 5th largest production yacht builder with a fleet that ranges from 16m to 46m. The Vision 68 is a new model within the Vision range which goes up to 24m.

Xanthos 7.8m 50kn RIB
Originally briefed as a governmental agency/security patrol craft, intended to carry 12 armed personnel at 40knots, but with an option to be configured as a leisure or sports RIB, the first hull has been fitted out as a private vessel. Early reports indicate 53knots was attained with a single 350hp outboard, running in light payload configuration, and the picture above confirms the lifting strakes aft are doing their job as she runs chines dry at these speed and payloads. Balancing the hull form for high speed and a stable ride when light, against sufficient lift and power when laden, was an interesting challenge. Stimson Yachts provided naval architecture services and deck layouts for the patrol craft configuration, while local designers Orpheus drew the console and Haluk Suntay carried out the structures and systems engineering.

6.5m Fast Patrol Boat
Building on the success of the 11m BSF for SHM in Mumbai,  we were engaged to draw a 6.5m/35kn Fast Patrol Boat (FPB) for which they have a a 50 boat order on a tight timeline. Hull lines were issued at the start of August and hull no.1 was completed at the end of November 17. She was trialed successfully at the start of December, with hull no.2 close to completion at that time. The Technical Spec's called for shallow draft operations, high speed on modest power at full load and compliance with India Registry of Shipping (IRS) High Speed Light Craft Code (HSLC). On trials, powered by twin 115hp outboards, with a 10-pax payload the contract speed of 35kn was exceeded comfortably.

42ft Gamefisher
Spencer Marine launched this 42 Sportfisher in Auckland just before Christmas '17. Intended as a dedicated off-shore fishing platform, she has a 3,000lit fuel tank and twin Cat C12's (each producing 705hp at 2,300RPM) spinning Veem 27.5inch props fitted with interceptor tabs for adjustable pitch and interceptors for trim control at the transom She looks great in her two-tone grey paint scheme, and the word from the fishing grounds is she handles well, too. We will post pictures of her both underway when we get some!

11m Border Security Force Patrol Craft
SHM Ship Care in Mumbai engaged us to provide the naval architecture for this 11m Border Security Force (BSF) craft. The Technical Specifications made for a tricky set of criteria to fulfill, with a length, displacement and speed requirement that proved challenging in selecting the hull parameters and compliance with India Registry of Shipping (IRS) High Speed Light Craft Code (HSLC). The final hull model was both tank tested and analysed in CFD to validate our predictions. Following successful completion of seatrials exceeding the 25kn at 85%MCR, SHM in Mumbai have not been slow in delivering the first 6 of a 12 boat order to the BSF.

STRYDA 6m Amphibious Power Cat
Through our involvement with the ARC600 Amphibious Rescue Craft, we were asked by Stryda Marine to draw a power cat that would accept the Orion Marine S25 4-wheel amphibious system and deliver 30kn+ on 200hp. Built from aluminium to a high standard, Stryda marine took our hull design and added their deck and cuddy design to affer an unrivalled amount of deck space for fishing from. The asymmetric vee planing hull form was developed from our Infinity 8m power cat, and gives a very smooth ride in all seastates, allowing almost full throttle and 30kn in 1m seas – be that up seas, down seas, beam-on or quartering. One enquiry seeking a higher payload than originally designed for has led to the inclusion of a hydrofoil between the hulls to add to the dynamic lift. The effects have been to increase lift and therefore top-speed with an attendant reduction in fuel burn and motions in a seas way. We also carried out a CFD study alongside the practical evolution of the foil to minimise vibration at speed

Origami 560 RIB
“Optimistic”, an Origami 5.6m RIB, was launched in May and seatrialed in a mix of calm water and 75cm chop blown by 20kn seabreeze. She hit just over 31kn with a 90hp on the back – bang on the predicted numbers. Home-built by her owner from a CNC kit of engineered composite panels from Gurit, she is fitted with a half-round D-fender from Lancer. Her owner reports: “Thanks once again. What a great day testing. I am so pleased with everything.  Your support has been amazing and you have certainly gone the extra mile for me. You have designed ‘Optimistic’ with everything I wanted – she has more fishing room than anything of similar size, and I am so impressed with its handling! I can’t get over the soft ride – it is so smooth and docile. It’s an improvement on my previous boat, an otherwise very capable RIB. And with the water ballast tank flooded she is amazing in the rougher water. You have done a great job. It’s everything that I wanted!”

5.8m SOLAS compliant rescue boat
Certified by Lloyds Register as a SOLAS/MED compliant Rescue Boat for LY1/LY2, this 5.8m RIB doubles as a crew tender and so while compliant in every respect it is also spec’d as a superyacht tender. Given its primary role is as a rescue tender, features such as the deep-vee hull form with improved seakeeping characteristics for use in extreme sea states take precedent over the more aesthetic aspects. The Yanmar 4LH series engine and HamJet 213 installation is fitted with the SOLAS inversion kit, since as shown in the images the testing includes 180deg self-righting test as well as swing test, drop tests and swamping/flooding tests – after which the tender must be demonstrated to function perfectly.

Surtees 8.5m Widebody
Stimson Yacht Design and Yacht Studio are pleased to announce the launch of the new Surtees 8.5m aluminium fishing boat. Naval architecture, analysis and design engineering services were provided for the new hull and structure, with full size computer generated cut files being provided to Surtees Boats Ltd. The 8.5m is the largest model in the Surtees range and represents a technological evolution from their usual non-computerised build design and build process. It features their trademark waterballast system and bullet-proof construction, and cleared 37kn on sea trials with six persons aboard. Stimson Yacht Design and Yacht Studio worked closely with the Surtees design team to analyse, model and engineer the new boat, and look forward to working on future projects together.

8.5m Harbour Patrol RIB
The Cowes Harbour Commission’s RIB incorporated the latest generation Volvo D4/225hp inboard diesel and Hamilton 241 waterjet to allow both shallow draft operations, and a high bollard pull of ¾ tonnes to tow and retrieve disabled yachts; a stainless steel bimini and cage for shade and shelter, carrying instruments, flashing lights and the PA system; and dual fuel tanks (184 litres total). She comfortably exceeds the contract speed required by the Cowes Harbour Commission by 10%, and does this at an impressive 2/3 of the weight, with an engine 2/3 of the power of that specified by the competition, thereby cutting fuel consumption and running costs by 1/3 over the life of the boat.

11m Commuter Launch
This long and slender all-weather commuter aunch is based upon our proven 8.5m RIB harbour patrol hull, extended by 1.5m to a 10m moulded length. Fitted with twin 260hp inboard diesels and waterjets, and having the ability to take a mud-berth and operate in shallow water, she demonstrates exceptional manoeuvrability throughout the speed range. The solid PU fenders were selected over traditional inflatable RIB collars for reasons of additional robustness and low maintenance. Used as commuter launch year round, she has an enclosed cabin with seating for 8 persons, and is MCA certified for charter operations.

Kenton 91ft power cat
We are pleased to announce our collaboration with Chris Wong, a Shen Zhen-based yacht designer, on this 29m/94ft power catamaran for a Chinese client. SYD is providing the naval architecture, systems schematics, stability and powering analyses for this exciting project. With a 100 tonne lightship mass and top speed of 18kn, the composite engineering for the structure will be carried out by Gurit (Asia Pacific), and the vessel will be classed under Chinese Classification Society rules. The heli-pad forward, the hydraulic tender/diver lift and swim platform are just a few of the interesting features of this yacht.

Venue 30 luxury charter yacht
The Design Problem was to design a charter yacht built to superyacht standards yet offering unbeatable commercial viability. Many privately owned charter yachts have the principal objective of offsetting running costs, and their suitability for charter is often compromised by the owners’ personal tastes and choices. Stimson Yachts approached this brief by designing a yacht that was specifically to be used for charter, maximising accommodation volume and offering flexible spaces which could be used for a variety of functions. The result was a 30m motor yacht, catering for high class dockside entertaining of up to 100 guests (eg cocktails and canapés at the Cannes Film Festival) , inshore cruising for 60 (eg a sunset cruise for a wedding reception) or prestige accommodation for 10 (eg executive business training), all within a commercially viable platform.

7.5m RIB Superyacht Tender
Five of these superyacht tenders have been built from the design our original 7.5m RIB design, four featuring the innovative removable bow section. Stowed in the transom garage of a the 34m ketch SY SOJANA, a Heesen 47m steel motoryacht, and a 90m megayacht, the brief called for all-carbon construction, 260hp inboard diesel with stern drive for 40knots of speed, yet a 1500kg dry weight limit. Further functionality included stowing the bow within the RIB hull, and a folding console to meet the additional constraint of a 1.4m airdraft limit without deflating the tubes, plus features such as boarding step, integrated ski pole/boarding post. The motherships’ itineries all called for world cruising in remote areas where speed, seaworthiness and capability of the main tender are paramount.

Infinity 8m power catamaran
The Design Problem: To design a fast, beachable motorboat for the Caribbean, that is light enough to perform whilst being robust enough to deal with the sometimes rough Atlantic waves. Solution: Stimson Yachts designed a 26ft power catamaran. During sea trials she proved her worth as Indigo Yachts took her out in 6-8ft seas and 20knots of breeze: “Many times we came off the back of waves, expecting a slam, but Infinity just gently fell back into the water with a whooshing sound”. In March 2005, Infinity was used as an official water taxi for the St Maarten Charter Yacht Show, and following her impressive handling and comfort in such unpredictable waters, Indigo Yachts and Stimson Yachts have developed a 40ft version for another Caribbean-based client.

ARC600 amphibious rescue craft
Showing off Kiwi-ingenuity to its best, Auckland-based Orion Marine commissioned Stimson Yacht Design to draw a 6m/20ft hull to work in conjunction with their S25 amphibious leg system on an Amphibious Rescue Craft. The design brief for the ARC600 included requirements such as shallow draft, low wash, stability at rest and the ability to absorb a 1 tonne payload.The resulting cathedral hull form draws on our previous experience with landing craft, and attains over 20kn with a single 90hp outboard and two crew aboard, exceeding both speed predictions and handling expectations on seatrials. An excellent video of the ARC600 demonstrating its abilities can be found here.

6m RIB Landing Craft
The Landing Craft features a near rectangular plan form for a very stable platform with excellent load-bearing capabilities and maximum ramp width. With a lightship mass of c.1300kg and a top speed of over 30kn, the max payload of c.1300kg doubles her displacement and shifts the LCG up to 1m forward of the lightship location. This would wreak havoc with the handling of a conventional deep-vee hull form, but careful design of the cathedral hull ensured that the LCB shift was in sync with sinkage as the payload increases maintaining level trim through out the displacement range and similarly the centre of pressure of the planing bottom through the speed range.