How long does it take to complete one circumnavigation?

[belizesailor]

Originally Posted by chrisr

interesting...



however i feel that defining a motorsailor is a lot more complicated than just range. for example our catamaran has a range of over 1000 miles under motor and will do 10kts when we want to...but it's definitely NOT a motorsailor



there was another thread about this recently which it might be worth referring to



cheers,

Yep, larger cats can lope along quite nicely at 8-10 knots under power or sail. They could easily match Kasemier's 7 knot average. Add some well secured fuel bladders for longer legs or routes w poor wind.

Lots of good older used cats available on the market these days.

[Paul L]

Originally Posted by belizesailor

Yep, larger cats can lope along quite nicely at 8-10 knots under power or sail. They could easily match Kasemier's 7 knot average. Add some well secured fuel bladders for longer legs or routes w poor wind.

Lots of good older used cats available on the market these days.

I don't know, if you want to turn a seaworthy Cat into a dangerous offshore Cat, add tons of weight.

[belizesailor]

Originally Posted by Paul L

I don't know, if you want to turn a seaworthy Cat into a dangerous offshore Cat, add tons of weight.

Carefully positioned of course!

Diesel weighs ~7lbs/gallon. Most small boat engines burn 1-2gph at modest cruising RPM so you can add relatively a lot of range without adding a dangerous amount of weight.

[StuM]

Originally Posted by Paul L

I don't know, if you want to turn a seaworthy Cat into a dangerous offshore Cat, add tons of weight.

Tons? One ton total (not additional to normal tankage) of diesel is good for well over 2000NM.

[Adelie]

Originally Posted by Wckoek

I have just read about Eilco Kasemier's boat Bylgia II, just shy of 40 feet is the smallest powerboat to have completed a circumnavigation at under 7 months.
I think he stopped only in between for fueling and provisions.


I wondered for those who have circumnavigated, how long does it take for you to complete a circumnavigation?

Bylgia II was not the smallest powered circumnavigator, Half-Safe was only 15'2". Admittedly is was a lot slower, but the trip was more interesting.
https://en.wikipedia.org/wiki/Ford_GPA

https://issuu.com/k-c-mediaworks/doc...navigator01/52

[Wckoek]

Originally Posted by StuM

Tons? One ton total (not additional to normal tankage) of diesel is good for well over 2000NM.

A tonne = 1000kg = 1200 liters of diesel = 317 gallons.
My experience is that the most efficient trawler above 12 tonnes would achieve somewhere around 4 MPG, at sea I would gather it is around 3-3.5 MPG which makes around 300 gallons safe for more than 1,000 miles but not 2,000.
I don't know a lot about catamarans, but I understand that they couldn't carry a lot of weight, assuming they are much more efficient, how large a cat in terms of length or displacement to be able to carry at least 200 gallons of diesel?

[wingssail]

OK, I still don't have any idea why you want to do this, but here is a fast vessel with rig and keel to dampen rolling and waterline length to make 10ks of speed.

Add FUEL CAPACITY and go.

MacGregor 65, several available in a moderate range of prices, some with pilot house, and if you want to sail, 20kts.

[st0nes]

It depends on how fast you go.

[Paul L]

Originally Posted by belizesailor

Carefully positioned of course!

Diesel weighs ~7lbs/gallon. Most small boat engines burn 1-2gph at modest cruising RPM so you can add relatively a lot of range without adding a dangerous amount of weight.

So adding 600 miles range adds close to 1,200lbs with your numbers. A cruising boat doing a circumnavigation is already loaded down with extras.
I saw a sportfisher style powerboat pull out of here the other day. He had 9 square portable tanks tied to the deck, each with near 500liters. That's close to 4 tons of extra weight. They were doing Seychelles to Oman.

[Rimica]

Started in Greece in 2019, spent 6 months in the Caribbean in 2020, wasted a year on Covid and we restart in September 2021. We expect to be finished in summer 2024 for a total of 5yrs

[Adelie]

If the OP wants to add range without increasing weight, slow down.
Decreasing speed by 30% from hull speed will probably double your range.

[belizesailor]

Originally Posted by wingssail

OK, I still don't have any idea why you want to do this, but here is a fast vessel with rig and keel to dampen rolling and waterline length to make 10ks of speed.



Add FUEL CAPACITY and go.



MacGregor 65, several available in a moderate range of prices, some with pilot house, and if you want to sail, 20kts.

****! Have you ever been on an M65? Feels like its built out of thin plastic! Super flexi. I would get nervous more than a mile from shore!

[belizesailor]

Originally Posted by Adelie

If the OP wants to add range without increasing weight, slow down.
Decreasing speed by 30% from hull speed will probably double your range.

Yeah, but he also wants to go quickly. So he needs the range to at least match Kasemier's record while averaging 7 knots.

[Wckoek]

Originally Posted by wingssail

OK, I still don't have any idea why you want to do this, but here is a fast vessel with rig and keel to dampen rolling and waterline length to make 10ks of speed.

Add FUEL CAPACITY and go.

MacGregor 65, several available in a moderate range of prices, some with pilot house, and if you want to sail, 20kts.

I think you need to sail them with crew, actually there is one 70+ footer that is designed to be shorthanded available for sale in my neighboring country, just that it is too long a boat to keep.

Originally Posted by belizesailor

Yeah, but he also wants to go quickly. So he needs the range to at least match Kasemier's record while averaging 7 knots.

Not exactly, but I want to go anytime, pushing on even when there is no wind, rather than bad weather other peoples here are thinking about.

[belizesailor]

Originally Posted by Paul L

So adding 600 miles range adds close to 1,200lbs with your numbers. A cruising boat doing a circumnavigation is already loaded down with extras.

I saw a sportfisher style powerboat pull out of here the other day. He had 9 square portable tanks tied to the deck, each with near 500liters. That's close to 4 tons of extra weight. They were doing Seychelles to Oman.

I was thinking more along the lines of just adding some reserve. Countless times, due to circumstances, Ive cut it closer than I'd like on that last leg to landfall. Even a few jerry jugs makes a difference with a miserly engine.

For example, if you wanted to keep added weight at no more than 500lbs, then thats ~70 gallons of fuel. If the boat can make 7 knots at no more than 2gph then thats an extra 245 miles. That's not much if you want to cross an ocean under power, but it makes a difference if you are just trying to get across some calms to get back into wind, or if that last leg to landfall is calm.

Its also a judgement call. If I had a high degree of confidence that the initial leg of a crossing was going to be calm-ish before getting into wind then I might push the fuel load up a bit, motor like hell on the first leg, and burn off some fuel load before getting into wind.

This would give some more flexibility in route planning and help cut crossing times somewhat. For example cut across the edge of that High Pressure, and associated calms, rather than sail all the way around it.