Which boat would be good for me?

[ColinR]

I have a feeling that you are going to struggle to find the economy that you're looking for. I have a 22 ft planing boat and average one a season 4 to 5 gallons per hour at a usual speed of 20 to 25 knots. I don't think that is unusual. If you get up to around é0 ft you will get nothing like that.

[BruceK]

You're on petrol though aren't you Colin? Remember petrol is also reving much higher because it can't make the torque of a diesel at nearly half the revs. My KAD42s straight six 3.6 litre diesels average 5 to 6 gallons per hour each for a 7 ton 37 foot boat or 10 to 12 gallons per hour total at those speeds. The figure the OP gave was not unrealistic for a single on a 28 footer coming in at 2.5 to 3 ton I think. Not 100 percent sure, have no experience but seems plausible as 2 small engines are generally accepted as being 1.5 times more inefficient than a single big one.

[ColinR]

Yes I am on petrol but if you consider the difference between pushing a 22 footer on petrol with a 30 footer on diesel I would expect the fuel costs to be similar (approx)

The point is that you will never get a planing, or semi displacement boat that could be considered economical to run compared with chugging a yacht along on a small diesel. Unless you want to go everywhere at 5 or 6 knots.

[BruceK]

Yes, that is agreed. There is no free ride when it comes to speed in a apple v apple comparison. The point to remember is in hull speed. When you can only really make 5 knts on hull speed but the engine can push the displacement hull to 7 people tend to push 6 or 7. Just like planing boats this vastly increases consumption for very little gain. Also remember a yacht is merrily pushed to hull speed on a very small engine. 8 hp or less OB on your size vessel, but you will never see a mobo with such a small engine in. For the 30 foot class you will invariably find a 50 -80 hp engine in minimum for displacement vessels.

The point I was trying to get across though is the visual impact of fuel economy when a person says I use 2 gal/h you use 15 gal/h therefore I am more fuel efficient by a factor of 7.5. The disparity is actually far less than you think and although gal/h is the correct and accepted format sometimes a better perspective is given using mpg format. As when using mpg the disparity is probably more like a factor of 2. Anyway, it's semantics. Fuel costs are pretty much the smallest costs in boating so should not represent the deciding factor in a choice of hull type imo.

When I decided to ditch the sportsboat for a cruiser I researched the topic endlessly on account of fuel costs and more importantly sea keeping. I was extremely anxious that if I was to take the plunge and shell out vast sums of money that the family and kids be happy, safe and above all NOT SEASICK. I spent about 3 months researching this topic add naseum because I could find myself with a bloody big millstone around my neck if a) I couldn't afford fuel and b) the family did not take to it.

In the end the realisation came after all the countless pros v cons that there is a bloody good reason why in any leisure marina 95% of the power boats found are planing vessels. The pro's just vastly outnumber displacement. Of this figure you'd find maybe 1% at semi-D. And yes I very nearly bought a Swedish Semi-D, I am so glad I didn't. Then it came down to planing hull type, and for our waters the Deep V & Steep Rise combo worked out the best for sea keeping at all in at the OP's budget, £25k, 37foot LOA, twin engined, 6 berth in 3 cabins, 2 berth in cockpit loungers. Job done

[BruceK]

BTW. That last vid was done in a F8 in a wind with tide scenario (wave backs more gentle) on Sunday 1st May if you wish to corroborate . Note how stable the boat is even though it was a 1.5 m swell, 5 second period. Took me 1 hour 15 minutes from Caernafon to Conwy at 24 knts observing the various speed restrictions. I was on a club do with 5 other yachts. Took them 6 hours to get back with the wind in their favour.

[ColinR]

Agree with all of that and if you spend a day out on something like a semi displacement fisher like a bigger Arvor you'll really see the difference when you throttle up

My hull speed is something under 6 knots and you really notice when you try to get above that, until it hits planing speed when everything flattens out, fuel economy improves and my grin gets bigger

That Formula is a lovely boat by the way and obviously copes with the heavy stuff very well. Note to self when shopping for my next boat. Mind youthe Monterey copes pretty well in a chop as IanH will attest to when we had a little race down the Solent.

[BruceK]

Thanks for the vote on the Formula. I think we really struck lucky on that deal, and it has worked out very well for us on so many levels. And hopefully have given the OP something more to think about. As his current values (as stated) were exactly my values when starting out. Good luck to him in the search for his next boat.

[BruceK]

Oh btw, to the OP.

I cruise in company with the club yachts a lot. When doing so I switch off the port engine (the starboard engine has the steering hydraulics) and just idle along at 5 knots through water more over ground if working the tides. Fuel consumption is still about 6 litres an hour but it's a sedate and pleasant cruise with all the chill and zen factor of doing it under wind. In fact I will ride the tides like this frequently just to extend the pleasure.

You can see Amanzi at the 4 min mark leading the fleet