Hi and welcome jagdpanther, i`m sure ajg will agree that teh sheerline models are an excellent alternative to an engels kit , and even have some advantages !
first of all the hulls split in half right along the water line, inside is teh WTC , which is split into three sections, fore section houses pump,receiver and switching for pump operation, also front dive planes depending on the model,mid section is the tank, and aft section houses motor/gearbox speed control and servos for rear planes.
sheerline models use a pump system of diving, a (car?) washer pump pumps water into the tank,wjich will dive the boat. to surface air pressure in the tank ( slightly compressed due to water displacement) is allowed to force the water back out of the tank and hence surface , simple !! but it does work, access can be made to all parts of the system i required.
another good point is that the hull on sheerline models is a wet type, this means that the whole hull (apart from the wtc) has water in and around it when running, teh benefit of this is overall a much lighter model,
Engels use dry hull configuration, which means the hull is ballasted down very finely, when the tank draws water in ( like a big syringe) the weight of teh water again dives the model, however because teh hull is essentially a big bubble of air sealed in it`s very bouyant, and to take it to the correct level for diving takes a lot of ballast,
typically the Engel patrick henry has a starting ballast of 19 Kg ( inc all gear) !! this is before adjustment weight is added for fine tuning, in comparison the sheerline ohio ( a much bigger boat) has a start ballast of 1kg then fine tuning afterwards ( overall weight i think is about 12 kg)
Engels kits do seem to manage to have more detail on the hulls than the sheerline, but this doesn`t mean the sheerlines are devoid of detail, far from it .
There is a relative high degree of prefab work done on the sheerline models, about a weeks work is req`d for sailing, rc gear required .........
2/3 servos depending if model has front dive planes or not
Esc
6v/12v SLA depending on model
fail safe unit
2 0r 3 servo extension leads
tx/rx
no other special eqipment is required .
if you do go for one, you certainly won`t be disappointed .
Adz..