wakeup
Well-Known Member
Or you could even look at a wave piercing cat ??
A catamaran that looks good...
- Thread starter Whitelighter
- Start date
Major Catastrophe
Well-Known Member
I bet the raggies are scribbling in a mast and sails and salivating. /forums/images/graemlins/grin.gif
Bajansailor
Well-Known Member
Re: A catamaran with hydrofoils.....
Here are a few interesting links re foils :
http://www.hydrospeed.co.za
http://www.hysucat.net/catamaran/en.html
http://www.hysucat.co.uk
I think this big power cat might also have a foil :
http://www.argo-boats.com/jutson57_specs.html
And here are some interesting designs of power cats - it is a pity that the Prout Power Cats are not still being built.
http://admin.sun.ac.za/kie/unistel/technologies/applics.htm
Teknicraft in New Zealand have done a fair bit of work with foils - here are some of their boats :
http://www.teknicraft.com/motor-yachts.aspx
Have a look also at their passenger ferry designs - the hull forms of these could be used for a motor yacht :
http://www.teknicraft.com/islander.aspx
Here are a few interesting links re foils :
http://www.hydrospeed.co.za
http://www.hysucat.net/catamaran/en.html
http://www.hysucat.co.uk
I think this big power cat might also have a foil :
http://www.argo-boats.com/jutson57_specs.html
And here are some interesting designs of power cats - it is a pity that the Prout Power Cats are not still being built.
http://admin.sun.ac.za/kie/unistel/technologies/applics.htm
Teknicraft in New Zealand have done a fair bit of work with foils - here are some of their boats :
http://www.teknicraft.com/motor-yachts.aspx
Have a look also at their passenger ferry designs - the hull forms of these could be used for a motor yacht :
http://www.teknicraft.com/islander.aspx
Phoenix of Hamble
Well-Known Member
[ QUOTE ]
I bet the raggies are scribbling in a mast and sails and salivating. /forums/images/graemlins/grin.gif
[/ QUOTE ]How did you know?
I bet the raggies are scribbling in a mast and sails and salivating. /forums/images/graemlins/grin.gif
[/ QUOTE ]How did you know?
Major Catastrophe
Well-Known Member
/forums/images/graemlins/laugh.gif
MapisM
Well-Known Member
Don\'t!
I had a bad day in the office yesterday, just reading about your day out at sea already hurts more than enough....
Don't even dare posting also pics! Or maybe a clip...?
If envy could kill, you'd be dead.
PS: by 200 lph, do you mean for both engines, and at that speed? If so, that's actually not bad at all!
I had a bad day in the office yesterday, just reading about your day out at sea already hurts more than enough....
Don't even dare posting also pics! Or maybe a clip...?
If envy could kill, you'd be dead.
PS: by 200 lph, do you mean for both engines, and at that speed? If so, that's actually not bad at all!
MapisM
Well-Known Member
Yes, indeed.
And clever, also.
Particularly the arrangement of guests cabins, which exploits the full width also under the main deck, by lowering the floor laterally into the hulls.
An excellent med boat imho, though it might take years to be fully understood by its typical target customers.
And clever, also.
Particularly the arrangement of guests cabins, which exploits the full width also under the main deck, by lowering the floor laterally into the hulls.
An excellent med boat imho, though it might take years to be fully understood by its typical target customers.
Gludy
Well-Known Member
Re: Yes, indeed.
It seems we agree on this one Mapism.
The only thing I do not like is the lack of aft deck cover - making it as you say very much a med boat.
Has anyone any idea how a hydrofoil cat rides?
It seems we agree on this one Mapism.
The only thing I do not like is the lack of aft deck cover - making it as you say very much a med boat.
Has anyone any idea how a hydrofoil cat rides?
Bajansailor
Well-Known Member
Effect of hydrofoils
Re lack of aft deck cover, one could just put up a bimini type awning that could be easily folded away for those folk who want to barbeque themselves in the sun.....
Re how a hydrofoil cat rides, I think that the basic function of the hydrofoil between the hulls is probably to help dampen the pitching and heaving motions while under way - sort of in the same way that a foil stabiliser system works to prevent rolling on a monohull.
I do not think that the hydrofoil is designed or intended to try to lift the hull partially out of the water, eg to reduce skin friction drag.
The vessel would need pretty large foils in order to be lifted completely out of the water like the old Red Funnel hydrofoil ferries in the Solent.
I do know that all else being equal a properly designed catamaran generally has a much more comfortable ride than a monohull - this is partially due to the cushioning effect of the air trapped between the hulls under the bridgedeck. The hydrofoil simply works to make this ride even more comfortable.
Re lack of aft deck cover, one could just put up a bimini type awning that could be easily folded away for those folk who want to barbeque themselves in the sun.....
Re how a hydrofoil cat rides, I think that the basic function of the hydrofoil between the hulls is probably to help dampen the pitching and heaving motions while under way - sort of in the same way that a foil stabiliser system works to prevent rolling on a monohull.
I do not think that the hydrofoil is designed or intended to try to lift the hull partially out of the water, eg to reduce skin friction drag.
The vessel would need pretty large foils in order to be lifted completely out of the water like the old Red Funnel hydrofoil ferries in the Solent.
I do know that all else being equal a properly designed catamaran generally has a much more comfortable ride than a monohull - this is partially due to the cushioning effect of the air trapped between the hulls under the bridgedeck. The hydrofoil simply works to make this ride even more comfortable.
MapisM
Well-Known Member
Re: Effect of hydrofoils
Re. air entrapment effect, I'd expect it to be almost negligible at the speeds we're talking about.
That's something for boats like the Nortech mentioned by spannerman...
Hydrofoils can instead be effective at anything above displacement speed.
I gave a quick look at their site, and found the following statement.
Mind you, I wouldn't put my right hand on the percentages claimed... but the principle makes sense.
[ QUOTE ]
HYDROFOIL ADVANTAGE
...Innovation design ... developed a unique patented Hydrofoil system. Fitted between the two hulls, one forward and one aft, these hi tech wing-like shapes actually suck the boat out of the water, much like an aircraft wing sucks an aeroplane into the sky. Again, by helping to further lift the hull out of the water the catamaran is able to greatly increase its efficiency. This leads to a huge improvement of up to 20% in fuel savings alone. Again, 25% fuel savings over the same vessel without the optional hydrofoils.
[/ QUOTE ]
There is also an interesting pic:
Re.aft cover, judging from the following pic, I'd expect some full enclosure covers to be available - not only a bimini.
Of course the flybridge of a trawler-style boat would give more protection to the main deck, but that doesn't seem much worse compared to a typical planing flybridge, either.
Re. air entrapment effect, I'd expect it to be almost negligible at the speeds we're talking about.
That's something for boats like the Nortech mentioned by spannerman...
Hydrofoils can instead be effective at anything above displacement speed.
I gave a quick look at their site, and found the following statement.
Mind you, I wouldn't put my right hand on the percentages claimed... but the principle makes sense.
[ QUOTE ]
HYDROFOIL ADVANTAGE
...Innovation design ... developed a unique patented Hydrofoil system. Fitted between the two hulls, one forward and one aft, these hi tech wing-like shapes actually suck the boat out of the water, much like an aircraft wing sucks an aeroplane into the sky. Again, by helping to further lift the hull out of the water the catamaran is able to greatly increase its efficiency. This leads to a huge improvement of up to 20% in fuel savings alone. Again, 25% fuel savings over the same vessel without the optional hydrofoils.
[/ QUOTE ]
There is also an interesting pic:
Re.aft cover, judging from the following pic, I'd expect some full enclosure covers to be available - not only a bimini.
Of course the flybridge of a trawler-style boat would give more protection to the main deck, but that doesn't seem much worse compared to a typical planing flybridge, either.
Bajansailor
Well-Known Member
Re: Effect of hydrofoils
Re air entrapment, one would logically assume that it doesnt have much effect at say 20 or 30 knots - I used to think that - until I went on a couple of 'little' power cats - and it does appear to have a noticeable effect. The cats do seem to ride on a cushion of air. You do have to keep the throttles opened up though - if you reduce speed then she starts to want to slam.
Re the hydrofoil on the Innovation, sorry, I didnt see that write up on their web page - it looks like it does have a dramatic effect re lifting the hulls out of the water, and hence reducing resistance! One should bear in mind though that this hydrofoil could be vulnerable to floating debris like tree trunks (or semi submerged containers?) and might be prone to catching lobster pot buoy ropes....
Re the photo you posted above, the awnings all look pretty substantial - good cover from the sun there! When you live in a hot climate you try to stay out of the sun whenever possible....
Re air entrapment, one would logically assume that it doesnt have much effect at say 20 or 30 knots - I used to think that - until I went on a couple of 'little' power cats - and it does appear to have a noticeable effect. The cats do seem to ride on a cushion of air. You do have to keep the throttles opened up though - if you reduce speed then she starts to want to slam.
Re the hydrofoil on the Innovation, sorry, I didnt see that write up on their web page - it looks like it does have a dramatic effect re lifting the hulls out of the water, and hence reducing resistance! One should bear in mind though that this hydrofoil could be vulnerable to floating debris like tree trunks (or semi submerged containers?) and might be prone to catching lobster pot buoy ropes....
Re the photo you posted above, the awnings all look pretty substantial - good cover from the sun there! When you live in a hot climate you try to stay out of the sun whenever possible....
BrendanS
Well-Known Member
Re: Effect of hydrofoils
Opening the throttles to reduce slamming is not purely for cats though. Many powerboats will go better over chop and small waves with more throttle, though beginners often find that counter intuitive.
Opening the throttles to reduce slamming is not purely for cats though. Many powerboats will go better over chop and small waves with more throttle, though beginners often find that counter intuitive.
hobiecat
Well-Known Member
Re: Effect of hydrofoils
Great to see these posts!!!!!!!!!! Hydofoil on a cat is usually a foil mounted between the 2 hulls that help the boat get on the plane earlier. Used on cat ribs a lot. Helps improve fuel consumption significantly.
Great to see these posts!!!!!!!!!! Hydofoil on a cat is usually a foil mounted between the 2 hulls that help the boat get on the plane earlier. Used on cat ribs a lot. Helps improve fuel consumption significantly.
Whitelighter
Well-Known Member
Re: Effect of hydrofoils
According to theor news section, they are launching a closed in bridge version soon as well.
According to theor news section, they are launching a closed in bridge version soon as well.
MapisM
Well-Known Member
Re: Effect of hydrofoils
[ QUOTE ]
Re air entrapment, one would logically assume that it doesnt have much effect at say 20 or 30 knots - I used to think that - until I went on a couple of 'little' power cats - and it does appear to have a noticeable effect. The cats do seem to ride on a cushion of air. You do have to keep the throttles opened up though - if you reduce speed then she starts to want to slam.
[/ QUOTE ]
Are you sure that the cruising wasn't smoother just because of a better planing speed, rather than air entrapment?
As also Brendan says, in some sea conditions you can experience a smoother ride at higher speeds also on monohulls.
I don't have actual figures handy, but as far as I remember the air entrapment effect is usually not even considered below 40kts or so, and begins to play a major role at 60+.
Some years ago, I had the opportunity to go for a spin on a lake with a 24' racing cat.
Two huge outboards, surface props, 110kts or so max speed.
I was at the wheel, with an expert friend (luckily!) as throttleman.
There are two distinct ride changes on such boats:
1) when they reach planing speed, but that's similar to any sport cruiser. Below that, the cruise is a real pain.
2) when air entrapment lift makes the hull drag practically disappear, and it feels like being on an airplane.
I'd call that a scary, rather than a comfortable ride!
You don't want to encounter an irregular wave in those conditions, can easily make the boat to really take off...
[ QUOTE ]
Re air entrapment, one would logically assume that it doesnt have much effect at say 20 or 30 knots - I used to think that - until I went on a couple of 'little' power cats - and it does appear to have a noticeable effect. The cats do seem to ride on a cushion of air. You do have to keep the throttles opened up though - if you reduce speed then she starts to want to slam.
[/ QUOTE ]
Are you sure that the cruising wasn't smoother just because of a better planing speed, rather than air entrapment?
As also Brendan says, in some sea conditions you can experience a smoother ride at higher speeds also on monohulls.
I don't have actual figures handy, but as far as I remember the air entrapment effect is usually not even considered below 40kts or so, and begins to play a major role at 60+.
Some years ago, I had the opportunity to go for a spin on a lake with a 24' racing cat.
Two huge outboards, surface props, 110kts or so max speed.
I was at the wheel, with an expert friend (luckily!) as throttleman.
There are two distinct ride changes on such boats:
1) when they reach planing speed, but that's similar to any sport cruiser. Below that, the cruise is a real pain.
2) when air entrapment lift makes the hull drag practically disappear, and it feels like being on an airplane.
I'd call that a scary, rather than a comfortable ride!
You don't want to encounter an irregular wave in those conditions, can easily make the boat to really take off...
Bajansailor
Well-Known Member
Re: Some more power catamarans that look good...
Here are a few more interesting (well, I thought they were) websites re bigger power cats :
http://www.proboat.com.br/powercat_show.htm#
http://www.sportfishingmag.com/boats_detail.jsp?ID=76976 - although the website for the boat mentioned does not seem to be functional
http://www.alwoplast.cl/Pdf/Summer2002-ThePowerOfMultihulls.pdf
Have a look also at their main webpage for other boats.
And here is a range of designs from Jutson Marine that seem to be similar to the Innovation cats :
http://www.jutson.com/
Their 54' power cat can do 24 knots with 2 x 230 hp diesels, and they quote some reasonably good fuel economy figures, especially when cruising at 12 knots.....
And finally for now some Powerplayers at http://www.powerplaycatamarans.com.au/
Here are a few more interesting (well, I thought they were) websites re bigger power cats :
http://www.proboat.com.br/powercat_show.htm#
http://www.sportfishingmag.com/boats_detail.jsp?ID=76976 - although the website for the boat mentioned does not seem to be functional
http://www.alwoplast.cl/Pdf/Summer2002-ThePowerOfMultihulls.pdf
Have a look also at their main webpage for other boats.
And here is a range of designs from Jutson Marine that seem to be similar to the Innovation cats :
http://www.jutson.com/
Their 54' power cat can do 24 knots with 2 x 230 hp diesels, and they quote some reasonably good fuel economy figures, especially when cruising at 12 knots.....
And finally for now some Powerplayers at http://www.powerplaycatamarans.com.au/
Bajansailor
Well-Known Member
Re: Some more power catamarans that look good...
Rather than edit the above post, and having all the website addresses going bananas, here is a good site that answers many popular power cat questions : http://www.twinveeboats.com/faq2.htm
Rather than edit the above post, and having all the website addresses going bananas, here is a good site that answers many popular power cat questions : http://www.twinveeboats.com/faq2.htm
ccscott49
Well-Known Member
What a horrible looking piece of excrament!
Whitelighter
Well-Known Member
I presume you also think that of modern flybridge boats as well?
Bajansailor
Well-Known Member
I have been a powercat browsin' again....
http://www.aventure-catamaran.com/index.html
I did a search on Yachtworld for 'new' power cats up to 70' for sale, and it came up with 218 boats - okay, some of them are obviously not new, but it is a pretty good representation - have a look at
http://www.yachtworld.com/core/listing/c...ed=-1&ps=30
An interesting range of Kelsall designed cats at http://www.kelsall.com/powercat.html
More fast cats with foils at http://www.stealthyachts.com/
I think I have mentioned Jutson before, but here they are again - http://www.jutson.com/
http://www.aventure-catamaran.com/index.html
I did a search on Yachtworld for 'new' power cats up to 70' for sale, and it came up with 218 boats - okay, some of them are obviously not new, but it is a pretty good representation - have a look at
http://www.yachtworld.com/core/listing/c...ed=-1&ps=30
An interesting range of Kelsall designed cats at http://www.kelsall.com/powercat.html
More fast cats with foils at http://www.stealthyachts.com/
I think I have mentioned Jutson before, but here they are again - http://www.jutson.com/
