Hurricane
Well-Known Member
Thats an interesting concept - the shaft enclosures could be antifouled as well and save on both economy and maybe some maintenance costs.
IPS IPS....Where Art Thou IPS ?
- Thread starter oldgit
- Start date
Thats an interesting concept - the shaft enclosures could be antifouled as well and save on both economy and maybe some maintenance costs.
kashurst
Well-Known Member
if the shafts could be enclosed and still use rubber cutlass bearings then maintenance issues would be simple. It would need to either use the raw water from the engine to run down the inside of the tube and through the cutlass bearing or have some clever shaped end to permit water through cutlass as the boats moves along.
PowerYachtBlog
Well-Known Member
Andrew38
Well-Known Member
Same with my Beneteau - I'm having to retrofit a bow thruster
Bandit
Well-Known Member
I go back to my earlier contribution a hull needs to be optimised to the type of drive.
You cant have a single hull that can be fitted with shafts, outdrives or waterjets and be fully efficient and optimised, it will be a severe compromise for two of the three.
Each form of drives has its advantages and disadvantages.
I have only driven two IPS boats and its manoevrability was awesome, I have twin shaft plus bow and sternthruster and that is pretty good but lots of levers, I reckon even my wife could drive an ips with joystick after half an hours training, ( i would not let her berth my current boat in a tight spot).
When I worked with Hydrofoils our boats all had a p bracket and a cutlass bearing on the after foils, some italian boats had the same shaft arangement but the shaft terminates in a cutlass bearing on the after foil but the prop was ahead of the foil and therefore running in cleaner water, so less cavitation from disturbed water.
IPS is good in as far as the props run in clean water no shafts and p brackets to disturb the water ahead of the prop and the prop is providing thrust paralell to the boat line rather than pointing at angle downwards as shaft boats where say 15% of the thrust is not in the direction of travel but lost downwards.
Outdrive is good in as far as thrust again is forwads and not 15% downwards as shaft but props running in disturbed water.
I was involved in running water jet ferries and they are great and very reliable in constant use but the hull design , vessel weight and lcg are esseintial that they are correct to perform well , you also get lift from where the water intake is just in the same way that a foil running in water or an aircraft wing does, the position relative to the waterline for the jet outlet is also essential.
Horses for courses as they say, depends on the application, depends on the budget and each has advantages and disadvantages.
I have seen few problems with waterjets, lots with outdrives but serious fuel savings, and few problems with IPS but complicated and expensive without a large fuel advantage partially in my mind as I dont belive the IPS design and the boat design are optimised Ie a boat designed purely for IPS as drive.
You cant have a single hull that can be fitted with shafts, outdrives or waterjets and be fully efficient and optimised, it will be a severe compromise for two of the three.
Each form of drives has its advantages and disadvantages.
I have only driven two IPS boats and its manoevrability was awesome, I have twin shaft plus bow and sternthruster and that is pretty good but lots of levers, I reckon even my wife could drive an ips with joystick after half an hours training, ( i would not let her berth my current boat in a tight spot).
When I worked with Hydrofoils our boats all had a p bracket and a cutlass bearing on the after foils, some italian boats had the same shaft arangement but the shaft terminates in a cutlass bearing on the after foil but the prop was ahead of the foil and therefore running in cleaner water, so less cavitation from disturbed water.
IPS is good in as far as the props run in clean water no shafts and p brackets to disturb the water ahead of the prop and the prop is providing thrust paralell to the boat line rather than pointing at angle downwards as shaft boats where say 15% of the thrust is not in the direction of travel but lost downwards.
Outdrive is good in as far as thrust again is forwads and not 15% downwards as shaft but props running in disturbed water.
I was involved in running water jet ferries and they are great and very reliable in constant use but the hull design , vessel weight and lcg are esseintial that they are correct to perform well , you also get lift from where the water intake is just in the same way that a foil running in water or an aircraft wing does, the position relative to the waterline for the jet outlet is also essential.
Horses for courses as they say, depends on the application, depends on the budget and each has advantages and disadvantages.
I have seen few problems with waterjets, lots with outdrives but serious fuel savings, and few problems with IPS but complicated and expensive without a large fuel advantage partially in my mind as I dont belive the IPS design and the boat design are optimised Ie a boat designed purely for IPS as drive.