I own both. Siesta, my Chris White Atlantic 42 has two Yanmar
27 HP 3GM30s. My PDQ 36 has two Yamaha 8 HP High Thrusts. The PDQ is 1.5 Knots slower than the Atlantic, and burns more fuel. That's OK since there are more places to buy gasoline on the East Coast
, the Bahamas
, and the Caribbean
. Net difference = zero.
I carry fuel for Siesta's dinghy in plastic Jerry Cans, But can fuel the PDQ's dinghy from the much safer main tank. That would make the purported hazard of gasoline the same, if there really was a hazard. Statistically, none exists for bridge deck
There are no 30 HP outboards that are as fuel efficient as Yamaha's High Thrust 8s and 9.9s. They are all geared and propped for max power in the 15 to 20 knot range of speed thru the water. Thirty six or seven feet LOA
, and 10,000 pounds cruising weight is the upper limit for twin outboard
engines on cruising cats that want to go seven knots. They key here is to find an outboard engine that reaches its rated power at the optimum cruising speed of the vessel. Putting bigger motors on a cruising cat does not equal higher speed, while pushing into wind and waves just wastes more gas (and life expectancy) as the higher boat speed motors ventilate or cavitate, or both!
There are lower power diesels that are perfectly suited to cats under 10,000# and 38' over all, they are quite expensive and much more difficult to work on down in a hole than an outboard is when its sitting in your lap. This advantage doesn't apply to outboard motors over 30 HP, so for the time being, bigger Production
cats can't use outboards. This is a shame, because four consecutive outboards are cheaper to buy run, and maintain than a diesel
, which costs more than four times the installed price
of an outboard, and has a reasonable life expectancy of less than those four outboards. Add the cost of folding props to the diesel
, and the argument is moot. Net difference earns a point for the outboards on a lighter cruising cat.
Cruising cats sail. If they didn't, they couldn't reach many of the places we want to go. Outboards (and sail-legs) lift
out of the water, but diesel cats drag a lot of hardware
in the water when they are sailing. The PDQ 36s with diesel engines are a bit more than a knot slower than the outboard versions, which were more popular by a 3:1 ratio. net difference = another point to outboards.
Diesel motors can turn really big alternators, yielding lots of amps for electrical appliances
. We often overlook the fact that those alternators rob a lot of horsepower from the 'prime movers'. That fact needs to be included on a comparison spreadsheet. Outboard motors put out enough amps to recharge their starting batteries, run some lights, and a GPS
. That's OK because there really isn't room on a mid-thirty-foot cruising cat for washing
machines, dive compressors, and ice makers.
This is where we insert the tie-breaker; the portable 2000 - 2500 watt gasoline generator
. My Honda
eu2000i recharges the house batteries, runs the microwave, the coffee pot and the air-conditioning just fine, sips gas is not very loud, but IS very reliable. Net score = outboards (and a portable generator) win every time.
But there is one criteria remaining, powering into adverse wind and seas. I have two experiences to relate.
1. On the PDQ 36 we were caught in a sudden Chesapeake squall. The genoa
tore out. We sailed on the main until we reached the river to return home. The wind was blowing 30 and gusting to 40, with short period 4' waves straight down the river. Tacking was out of the question. I fired up the two elderly 9.9 HP Yamahas that I had been nursing along for two years, set the throttles at full, and pointed home. We made 1 or 2 knots into the eye of the wind. We continued to make way up river until the surrounding trees and cliffs provided enough shelter to finish the trip. Five other boats, monohulls from my sailing club had to turn back, and anchor
out half the night.
2. Heading south with the Caribbean 1500
on Siesta after a hurricane
plowed its way up the Coast, we tried to hug the coast to avoid the Gulf Stream
and its tailwind. We headed east to clear the Shoals of Cape Hatteras we found ourselves in some very uncomfortable weather, at night. The Port engine (not the critical engine) quit and would not start. We spent two exhausting hours trying to get the main down, because we couldn't hold into the wind. This experience would have been avoided if there had not been a bit too much wishful thinking in the decision to press on.
The moral of these two stories is this: a smaller cat with outboards can handle serious adverse weather without over taxing the crew. Sometimes. a knot is enough. And the best equipped vessel can't handle the worst that can come from poor seamanship.
To finish the Cape Hatteras story, we go the main down to the third reef, and motor-sailed to the Charleston Harbor entrance, took a tow from TowboatUS, and spent 4 days licking out wounds before continuing the trip. We had straddled some Hurricane
debris and partially flooded the engine room through a hole almost 5 feet above the waterline!
All the planning and preparation in the world cannot surmount what Mother Nature can dish out, but do your best to keep her happy.