Ian Ellis of MacDuff Ship Design admitted straight away that the little ''Tservis 1'' and two port tenders destined for Turkey “weren’t something we’ve done before”. However he went on to say “it was actually a lot of fun to design”.

Built by RMK at Tuzla, the owner is part of the same group as the yard itself: the pair of boats being used for general purpose personnel transfer and supply duties around the eastern end of the Sea of Marmara. In fact the area is notable for its ship repair yards, RMK itself being noted for both its naval and commercial build and maintenance facilities.

Interestingly, the two vessels are part of a larger order which also include five 10.10m mooring assistance tugs and two 19m shallow draft ASD tugs, all designed by MacDuff. However, this pair of 14.90m boats didn’t conform to the more usual full displacement shape that MacDuff is better known for – and it presented the company with an interesting puzzle to solve.

First of all the steel hull needed a fairly substantial bow as both Tservis’ have to be capable of “nosing” between moored boats on their way to deliver either technicians or cargo. However, he went on to explain the contract was actually for a semi-planing form as the operators also want to get across the Turkish harbour at a fair pace – so the vessels had to be capable of a 16kn transit speed.

Further, Mr Elllis added that the owners “wanted to keep engine power to a minimum”, so the propulsion is supplied by Volvo Penta D16-750s, efficient 4-stroke direct injected, turbocharged and aftercooled diesel engines. Running at 1,900 rpm these each yield a modest but utilitarian 552kW of crankshaft power: what’s interesting is that the choice has been for systems that are notable both for their resilience and efficient running even at part-loads. This ‘robust’ choice equally applies to the Twin Disc Marine Transmission MG-5145 gearboxes which control the 850mm diameter Teignbridge propellers – and Halyard’s wet, water-injected exhaust system.

On top is a sizeable wheelhouse including seating for eight passengers behind the two crew (with a toilet facility below decks): this is because a significant portion of Tservis 1 and 2’s duties will be ferrying technicians around the yard and harbour to carry out work on visiting ships.

Mr Ellis pointed out that at around 7m long this superstructure runs to almost half the length of the boat; therefore meeting all the necessary specifications along with the speed requirement “was a bit of a challenge”. More, he added that looking to other designs didn’t really help: “A lot of the other similar vessels are based on planing hulls which are designed for higher speeds: they have a very fine entry and they also tend to be longer for the beam as well - but you can’t have everything so we needed to decide what to focus on.”

So the team, faced with these somewhat conflicting requirements, “went through a couple of iterations with the design”.

While these boats are not exactly high speed craft the UK’s Wolfson Unit also chipped in with some of its expertise: this helped finesse the shape and in the end although the original design’s rounded bilge was retained, the hard chines that had dominated the form further back were dropped in favour of a flatter aft section.

Giving the boats stability on the plane are Humphree Active Interceptors which improve speed, enable leaning into the curve while cornering and also lend some roll mitigation in larger waves.

On deck there is space and lashing points for five tonnes of cargo – another part of the service vessels’ remit – along with a small Toimil Marine cargo crane, model T-055M/2 for moving supplies: this can lift 700kg at 6.85m outreach. The anchor windlass came from Data Hidrolik Makina Sanayi AS. Underneath this, the Kohler Power Systems 28EF0ZD auxiliary genset supplies 28kW, 35kVA for the onboard draw.

Happily the first boat out of the yard performed well, said Mr Ellis, adding that until you get the results of the trials “there’s always a little uncertainty, especially when you have a new design and there’s a contract speed to be met”.

This is all the more so when a vessel pushes away from an established comfort zone. He added that though this design’s divergence from the norm posed something of a challenge it should help MacDuff in the longer run: “A lot of the time you have something that works for you that you can use as a stepping stone - not in this case.” But, he added having worked through the design, MacDuff now has another element to offer its clients.

Tservis 1 was delivered earlier in the year and the second vessel, Tservis 2, was handed over in the summer.

By Stevie Knight