Boater On Thames
Well-Known Member
Looks like the only problem is that can not get on and off the boat from sideway. Not even from the sideway to the swimming platform as it is blocked.
Very Intreresting Design Boat: Conam Chorum 60
- Thread starter Boater On Thames
- Start date
markc
Well-Known Member
I never get off mine from the side decks in the med, they are always too high, occasionally from the bathing platform when paying for fuel though.
Hurricane
Well-Known Member
There you go - internal stairs again.
Why did/do boat builders remove them from their designs?
They are one of the most practical things that were ever designed into that size of boat.
markc
Well-Known Member
Except on the Conam 60, both are external
Bajansailor
Well-Known Member
The Princess X 95 reminds me (a bit) of a much smaller 28' boat built in the USA in the 70's called the Cutter - here is a link to a thread I posted about it some years ago.
The Cutter 28 - a 70's version of Benjenbav's Steelaway
The Builder's head honcho even drove one across the North Atlantic to prove to many skeptics that she was seaworthy.
The Cutter 28 - a 70's version of Benjenbav's Steelaway
The Builder's head honcho even drove one across the North Atlantic to prove to many skeptics that she was seaworthy.
Boater On Thames
Well-Known Member
Saw one of the Conam boat has a V shade extension tab on the transom. What is this for? Never seen anything like this before.
Portofino
Well-Known Member
It’s retro fitted bolt in flap done by the factory .
Narrow beam but long boats with a reason deadrise suffer from lack of lift .
Or turned around too much stern suction .
After they grafted the stern section from the donor hull ( remember a patrol SD craft much shorter ) - sea trialed it it probably sunk too much at the stern , or required almost full tab down to level the thing out .
There are , is optimum beam / length ratios and this fall outside these .
Good you brought this up .
A wonder round any marina or yard and you see all sorts of added after the event fixed flaps tacked on hulls .
Personally I think the forum knows my stance on this …….happy to repeat ….start at the hull form @ a prospective boat purchase. Not necessarily at the V ( deadrise angle ) but the whole form in particular any post hull #1 prototype add ons .
Although with this even @ a skirted show the graft lines of the stern are difficult for the exhibitors to hide .
For clarity i,am not being judgemental ie saying it’s a bad thing , just explaining what and why it is , how it came about .
Cost too much to pen new 60 hull from scratch - you know the buck , plug , moulds etc .
Also those under water exhaust locations I pointed out further up ^^^ will exacerbate stern suction .
You want those as far Fwds as poss ( with in engine room practicalities) not as far back given a blank sheet of paper .
Narrow beam but long boats with a reason deadrise suffer from lack of lift .
Or turned around too much stern suction .
After they grafted the stern section from the donor hull ( remember a patrol SD craft much shorter ) - sea trialed it it probably sunk too much at the stern , or required almost full tab down to level the thing out .
There are , is optimum beam / length ratios and this fall outside these .
Good you brought this up .
A wonder round any marina or yard and you see all sorts of added after the event fixed flaps tacked on hulls .
Personally I think the forum knows my stance on this
…….happy to repeat ….start at the hull form @ a prospective boat purchase. Not necessarily at the V ( deadrise angle ) but the whole form in particular any post hull #1 prototype add ons .Although with this even @ a skirted show the graft lines of the stern are difficult for the exhibitors to hide .
For clarity i,am not being judgemental ie saying it’s a bad thing , just explaining what and why it is , how it came about .
Cost too much to pen new 60 hull from scratch - you know the buck , plug , moulds etc .
Also those under water exhaust locations I pointed out further up ^^^ will exacerbate stern suction .
You want those as far Fwds as poss ( with in engine room practicalities) not as far back given a blank sheet of paper .
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Portofino
Well-Known Member
So why did they do it ?
I did not say it was bad or rubbish . Calm down PeteM
I said they for economic reasons adapted existing bucks / plugs etc .
The interesting dead-rise the narrow beam , long WL length means it will have a comfy ride within its patrol boat speed range .
More part the sea ride through than get lifted and try and ride up and over waves , as opposed to fall off and slam / bounce along .
Talking 17/22 knot range .It’s no speed machine but I bet it’s a comfy ride in a chop .
I did not say it was bad or rubbish . Calm down PeteM
I said they for economic reasons adapted existing bucks / plugs etc .The interesting dead-rise the narrow beam , long WL length means it will have a comfy ride within its patrol boat speed range .
More part the sea ride through than get lifted and try and ride up and over waves , as opposed to fall off and slam / bounce along .
Talking 17/22 knot range .It’s no speed machine but I bet it’s a comfy ride in a chop .
stelican
Well-Known Member
The hull extensions also help prevent rudder stall with transom mounted rudders
Portofino
Well-Known Member
Arh rudders
.Big subject!On a full planing boat ,yes by lifting the stern thus ……….decreasing the amount of trailing edge submerged into the wash .
As excess trailing edge dipping deep in boats planing with there bows sticking in the air ( like a lot of typical 14-17 M ) = increases the tendency to rudder stall .
They have already clipped a fair bit off the trailing edge as well if you look looking at the pic .
Another trick while on the rudder stall theme is to counterintuitively have a blunt leading edge .
Yes unlike a sail boat keel / rudder which is streamlined into the water flow , with a mobo s rudder behind the props a blunt leading edge = turbulence = reduces rudder stall tendencies .
Just incase folks wonder why there mobo rudders have blunt leading edges on there rudders ……well fast planing boats .
^ blunt leading edge of the rudder .
^
^ Full trailing edge ( TE ) .1- the running angle of the hull through the water is naturally low sub 5 degrees .Sufficient stern lift to raise the upper 1/2 of the TE out of the prop wash .
No need to clip it off like the Conan .
Extra wide / large lifting strips .Note the position of the under water exhaust ( top of pic just in view ) relative to the props = miles away .
But the main most important thing not shown on theses pics is the CoG as close to the CoL , ( centre of Lift ) by mid mounting the engines = balanced boat running it wants to lower its bow once it’s starts planing , it wants to run level , raise its stern , without any down flap
Does this sans any “ add ons “ .
So the rudders are not excessively submerged , in fact they arguably lift up too much .
Itama 50 hull running flat .
^ here we are rudder stall territory .Could you submerge them any deeper ?
If it had wings it would take off !
