Engine room 4 - What sized engine?

 What horsepower diesel engine should go into a wylo 35? (Displacement sailboat)

A general rule of thumb of "3 horsepower per ton displacement plus 3hp" (I read it long ago, in an Alan Lucas book or article somewhere?) seems to be a reasonable formula. 

(Displacement x 3) + 3 = engine horsepower

Also Eric Hiscock (p185 "Cruising Under Sail") confirms this with "3hp per ton" which allows hull-speed to be reached if needed and gives the ability to go against a headwind and sea.

So for a 7 ton wylo35.  (7x3)+3 = 24 HP. That's just the empty displacement though..

Add 2 tons of water, fuel, supplies etc makes 9 tons displacement (9x3)+3 = 30 Horsepower.

Wylo2's designer Nick Skeates states 25 horsepower maximum for the wylo32 footer (6.2 tons displacement), so 30HP for the 6.9 ton 35 footer seems reasonable to me. Going bigger than this would see a significant increase in engine dimensions/weight and costs.

Alan Lucas discusses correct motor sizing in his book "Fitting out mechanically". The engine should "not be too small or too large" for the boat. It's best to run main engines with a fair bit of loading on them. ie Don't just run it to recharge a freezer or batteries (battery charging should only be a by-product of moving the boat along, other means like solar, wind or hydro used to recharge battery's so the engine can stay off)

Most boats have a comfortable "motor-cruising speed" where not too much fuel is consummed but the boat-speed is 70-80% of ultimate hull speed. A wylo35 hull-speed is around 7 knots, so "cruise speed" should be about 5-6 knots.

It's a good idea to be able to go at near-hullspeed for short bursts. This may be what it takes to get through a fast-flowing entrance into a calm safe harbor or coral atoll's lagoon. Engines have limited rated hours for which they can do this feat. For example the Nanni N3.30 is rated to run at full throttle for 1 hour out of every 8 hours run time.

"Over-powering" results in much higher installation/runing costs/repairs and an under-utilized too large engine suffers from this misuse. Large engine boxes enroach on accomodation. They require more fuel, there is more weight aboard and less storage capacity for other things.

"Under-powering" seems to be more common.  Motor cruising speed is too slow, especially if theres a headwind/ head current.  So full throttle is perhaps used too often, resulting in more rapid engine wear and repair bills. Another problem is if your anchor drags in a gale, underpowered boats just can't make any progress against gale force winds, or may even loose steerage way altogether and blow away out of control, not good in some crowded places or near a rocky lee shore.

Some home-built boats are "overbuilt" during construction or fittout, which can raise their displacement above the designed displacement. This must be taken into consideration if buying a second hand homebuilt boats (Not usually a problem with production boats in general, unless they were originally sold at hull only stage).

Engine room 3 - Marinized diesels

Marinised diesels are usually based on an automotive (car) engine and have a few things added on to allow them to operate in the marine environment.

They are usually lighter weight, more compact, less costly and spare parts are more readily available/cheaper than standard "marine diesels".

Marinised engines have freshwater cooling, either by a saltwater/fresh heat exchanger on the engine or a "keel cooler" outside the hull. As a result the engines walls/housing can be allot thiner and lighter than marine diesels, as very little internal corrosion occurs. 

Kubota (Japanese) diesel engines have a very good reputation and are used in industry and agriculture ashore. If they are marinized properly, they make for reliable and economic propulsion at sea. Spare parts are readily available and are more cost effective than pure "marine diesels"

Nanni Marine diesel engines have a kubota base motor. They are made in France and I've heard that they are reliable, have quality long lasting parts and can supply everything from propellor to controls. The 29HP "N3.30" has a 3 cylinder 1123cc engine and runs at 3600rpm maximum, peak torque is 2600 rpm. It's size dimensions are not too big leaving more room inside.  They have keel cooling option. It runs a 12V 120A alternator, mechanical gear box and maximum 15 degree propshaft angle and weighs in at 145kg.

Nanni N3.30

Nanni also has a larger 37HP "N4.38" with a 4 cylinder 1498cc engine. It runs slower at 3000 RPM maximum and has a wider useful torque curve. It has larger size dimensions and is heavier than the 29HP but is rated for more usage and more hours per year than the 29HP. 

Beta Marine (UK) might be a good option. The Beta 25HP   has a 3 cylinder 898cc Kubota , weighs 113kg and often swings a 14" diameter 3 bladed prop (but it's best to supply boats specifications for correct prop) . The Beta25 is very compact and serviceable parts (oil filters, electrics etc) are easy to access.

At least a couple of wylo's have Beta Marine engines fitted. There is a distributor/service center in Sydney, Beta diesel Australia.

Witchards Marine (Sydney, Aust) make WM28. , 3 cylinder Kubotas with larger 1123cc displacement, larger size dimensions and swing a slightly larger prop. (The WM22 is a 898cc but 22 horsepower might not be enough for a wylo 35?)

 For those with technical skills and a flair for DIY, car engines can be marinised. Nick used his van's petrol engine. Heard of a VW golf diesel installation too.

Kerosene pressure stove

 Bought a secondhand "Handi" stainless steel kerosene stove for wylo, around 1980's vintage.

I heard about it through a mate on the Investigator563 online forum, for sale in Newcastle, NSW. (1600km south as the crow flies) Contacted Gordon the seller, he told me it was removed from a yacht during refitting/upgrade, the yacht had done a 6 year circumnavigation with this stove. It had sat in the shed over 10 years. It was shipped up north by land and arrived at the couriers base in a nice plywood box that Gordon had made up.

Two burners are on top and a third burner is inside the oven. It has adjustable pot fiddles and came with accessories/spare parts and a separate large kero tank attched with a flexible hose.

After cleaning it up a bit, it all connected up and it fired up first go!! (must have been well maintained, thanks again to Gordon).  

To operate it involves pressure pumping the kero tank with a bicycle pump, preheating the burner(s) with methylated spirits (alcohol) and opening the burner valve knob (s). There are preheating cups under each burner and it came with a neat little alcohol bottle with long spout.

Kerosene is a safe fuel onboard as it takes allot to ignite it, but once lit it has a very hot burn. Kero also stores well for ages and takes up less space/weight due to high calorific content. Kero is readily available in remote ports too. The only cons are, it takes a few minutes to light up, some people don't like the smell of it and it has unusual maintenance requirements compared with gas. 

I want to steer away from propane gas onboard due to explosion safety hazard, bulky large gas bottles on deck, and high cost/lack of of refills in some remote places (also different incompatible gas fittings overseas etc)

Kero stoves like this were once popular back in the bygone era on remote outback off-grid cattle stations (ranches). They also had kero refrigerators, kero heaters and kero blowlamps. It was the fuel of choice before the modern "propane gas" (and gas pipeline) era. 

I priced the new modern kero equivalents of my Handi stove (eg Taylors in UK) and they cost  thousands of dollars new. My old one represents good value then. 

Handiworks factory began production in the 1930's, was located in Brisbane, Queensland but closed down late 20th century. The burners etc are essentially the old kero "primus" type which are still made in places like India.

Another second hand buy i made locally was a 1950's Primus No1 kero single burner pressure stove. It's not running and needs some fettling (new pump cup, maybe a burner head). It's similar to the one Sir Edmund Hillary and Tensing Norgay used when they summited Mt Everest for the first time.

On a wylo this type could be fitted to a gimballed heat resistant box (like on wylo2 "Io") 

To this longterm end, i built a "stove box", around 1 foot on each side. The box is made of plywood, has a 6mm cork tile insulating layer and inside has a 0.6mm aluminium sheet layer which reflects the heat. For now it's the galley on my 18ft trailer sailer and houses alcohol stoves (Trangia 27 or 25, pots , kettles) or Bonetti "can2001" for frypan cooking. It has a hatch-like lid which doubles as a non-skid cork trivet hotpot bench surface with fiddles when removed. Built a companionway-like front board for the box which also turns into another cork hotpot suface.

Portable galley box aboard Teria - Trangia 27 spirit stove