Cruise speed of early 80's 27's

[fairtide]

I owned the A27 Sport Cruiser with the Nissan LD28 engine rated at 78 hp. I found that it could move the boat thru still water at over 8 kts without actually running at top rpm. I rarely pushed the engine, however, as it was inefficient beyond hull speed where the sweet spot for the boat seemed to be. At higher than hull speed, the stern squatted into the water and "I think I can" never brought the boat out of the hole to where it would not be subject to displacement speed. Much of the fuel went into generating an impressive wake, but not much to speak of in an increase in speed worth the extra fuel burn and wear and tear on the engine and drive train.
I enjoyed the 27 without asking it to get me somewhere in a hurry. Its place in the boating world, I think, was to get me where I was going safely and economically. As you may have read in this group site, I traded for a 28TE and, I hate to admit it, I still run the boat at displacement speed when I have really nowhere to go, but I just want to be moving over the river.
With low powered engines, be prepared to enjoy the economy and not be concerned with speeds greater than the physics of the hull and engine combination were designed to deliver.

[Dave]

I was out last week in my 27 with the 160 Isuzu engine, there was a stiff offshore wind creating 3-4 foot chop, we were cruising along at about 8 knots into the waves and the bow was only moving up and down a couple of inches, meanwhile the speed boats were bouncing around like toys and we were leaving them in our wake. So given the right conditions we have one of the fastest boats in the bay.

[tranmkp]

Ill jump in - It really makes no sense pushing these boats past their water line speed - the formula gives us 6.67 knots -

so be happy with it - I took mine out in the bay the other day - it was like oily glass - at 6.7 to 7knts - there is NO wave - the water just leaves a flat flat run. That what you want to prop for - I thought the old dude who had the boat before had over pitched the prop. I was wrong. Peak torque for the Westerbeke 70hp is at 1800 (very quiet) prop for your torque and all will fall in place

for example - A 27 only needs 13 hp to reach hull speed in smooth water - double it for waves and wind and current and you have 26hp. I look where 26hp is on my engine curve - boy - plenty left.



I look at my power curve and see that Im using about 50hp and peak torque at a very low fuel burn. I know a 18x15 on a hurth 1-5 will nail the 1800 rpm cruse speed - So Im not overworking my engine.

[Jeff Lavallee]

Fairtide,
That is the engine I have. I just bought it in November and only had time to get it covered. Any advice you can give me for the Nissan?? Any problems with it when you owned it??

[Veebyes2]

This is my ex, a 1986 with a Westerbeke W100, at speed. Loaded for a weekend it would top out at near 13kts. It is at about that speed in the pic.

The 27s do plane, in their own funny way. Look carefully at the bottom from the stern & you will sell a 'hook' in the bottom, sort of a built in trim tab. There are some fast 27s around. I've been on a 27 Sport with a Cummins 210hp in it. Waterskiing anyone? That sucker would do 18kts!

[tranmkp]

Vees,

I can imagine you have many a caper under your belt!! Like you say, plane in a funny way - that built in trim tab is because the mold warped when they made the plug for the boats according to Joe P, the designer. I have had mine to 12.5 and it was some kind of storm and fury. Very hard to steer. Dont know why Id go that fast anyway... You must have had some kind of prop on the boat - Do you remember the pitch and size?

Say, Whats life like in Bermuda?

edit -- Whoa!!! I just looked up home prices in Bermuda!! Golly Moses Vee - you should be driving a Hinckley!!!!!


Cheers

MKP