Design/Build Nightmare

Since I am going to continue this I am stating a new topic. How many out there have Nightmare kits or some other model. I also have the plans for 2M Midnight Oil which is similar to Ghost Train. Nightmares x-sections are circular below the W/L, flat sides, flat top rounded corners similar to monohull or most full size tri’s I have pictures of. PULSE is egg shaped, flatter top/btm becoming boxy in the rear. amas V - 25 degree, box top/sides. WRTm40 egg shape flatter top/btm - amas similar. Ghost Train egg shape - fat top - amas opposite. Freight Train egg shaped, fat btm. amas opposite. What are your thoughts on these designs. All members invited.

Over here we are experimenting with several designs. We have Ghost trains,Snapdragons and other home designs as well as modified Snapdragons that we race. We know these boat’s are fast. The known designs are very good for beginner’s. The big thing that we found after travelling to a different area, was that weight of the boat is paramount for the conditions that you are in.

Picture this for a moment. 3-5 knots of wind. Three tri’s of different designs all hit the start line at the same time. Boat weights were around 2.5kg, 3.5kg and 4 kg. All boat’s were hit by a gust of slightly heavier strength (1-2knots), all the boat’s excellerated, the 2.5kg boat stayed with the gust and just kept on sailing away while the other two with the extra weight sailed out(lost) the gust. This happened all day, it was amazing how much speed difference there was.

Conclusion build your boat regardless of the design as light (but not to light) as possible for your conditions. It is easy to change down rig’s when the breeze comes in. Weight can be added to light boat’s. I thought that three kg boat’s would be ideal but this has been proven to be wrong. I admit that I was wrong with this thought. It seems to me now that building down to around 2kg (but not below) is ideal.

On designs themselves. We have found that the Snapdragon is quicker in light winds than the Ghost Train. When the breeze comes in however the Ghost Train is more stable. I would say that this all comes about from wetted surface. The Snappy’s are narrower than the Ghost’s which suit’s the lighter breeze. The Ghost’s seem to get “stuck” to the surface of the water in light winds. Wide boat’s are ideal for heavier winds. They are far more stable, hold full rig’s with no problem and just go.

Hope this helps some-one.


What about the Freight Train and Ghost Train where the hull x-sections are upsidedown from each other. The Nightmare by the way weighs 2.32 kg and is narrower than the Ghost Train.

I now very little about the Freight Train and haven’t seen one sail so I won’t comment on it’s performance.

My guess would be that the Nightmare would probably sail about the same as the Snapdragon, but again without every seeing one sail I can’t comment on them.

The weight that you have quoted is that the sailing weight? batteries rig etc.


Dear William,
Dear Peter,

The original ‘Nightmare 48’, as it was designed by me - Ernst Zemann/Austria - in cooperation with Hannu Jarvela/Finland - in August 2000, had the following main design criterias:

  1. Overall weight ready-to-sail: 2.5kg including rc-set,sailwinch and batteries. -

  2. As suggested by Hannu,
    I aimed for an even lower overall weight, for the possiblity of additional ballast for stronger winds ->
    -> for"Code RED"

  • which is only building number TWO - I reached 2.2kg overall! -
    This leaves 0.3kg for possible ballast in heavier conditions! -
    (2.0 kg overall are now possible with more building experience, but I would still vote for stiffer crossbars for less boat torsion and try to keep the weight -…-)

Hannu now simply uses a pack of small batteries in lightwind conditions - and a bigger battery pack in stronger winds. -
As it is planned in this design, the batterie pack is stored just about 4"/10cm forward of the mainhull stern -
this creates the biggest benefit for longitudial and diagonal stability for this trimaran. -

  1. For ease of construction, I choose 12 cross sections of 4"/10cm for mainhull AND floats + possible 2cm for the bowbumpers! -
    Counted from the stern, the thickest x-section of the mainhull is between section 4 and 5 -
    and for the floats between section 6 and 7! -

  2. In 2000 I did complete calculations of 6 or 7 different floats - and studied the relations of them to further 6 or 7 different mainhulls. - As we wanted as little surface as possible - wetted or not - we choose a mainhull of 4"/10cm width with straight flanges and rounded deck/side-connections. -
    (And a slimmer mainhull wouldn’t have enough space inside for a sailwinch AND my fingers -…-)
    This Mainhull of 10cm width creates exactly the 2500cm3 volume we wanted! -

  3. For the floats we wanted 250% of volume ->
    -> 2.5kg/2500cm3 x 250% = 6250cm3
    My calculations resulted in a float of 8.5cm width at the thickest cross section - with almost circular shape! -
    As we wanted a fully demountable model (for ease of transportation), I just flattened the top of this 8.5cm circle, to have a plain surface for crossbar installation - about 1"/2.5cm wide! -

6)Complete Floats - including all needed reinforcements and nuts - reached between 0.325kg and 0.375kg. -
Mainhulls reached from 0.5kg to 0.6kg - plus rc-set and sailwinch installation-board. -
Handmade CURVED crossbars 0.2kg to 0.25kg and straight crossbars from carbontubes 0.165kg to 0.2kg! -

I have re-calculated this original design last winter and completed sets of selfbuilding plans -
even for balsa-stripplanking of the hulls - are available now! -

But you still need to be capable of epoxy laminating ->
to cover those lightweight hullshells and to make your own crossbar fittings -…-
Please prepare for 200 hours of very precise building -…-

Best regards, Ernst Zemann

Download Attachment: [ F48 Nightmare 1.jpg]( Nightmare 1.jpg)

Professional shipwright - boatbuilder/-designer with 25 years of experience and a special interest in multhulls

Dear Ernst: I have MKI, III, IV, V. Are all the main hulls the same except for vertical nose height from 3 5/8" - 4 5/8" done by section middle? The amas on I and III look the same but I is 4 3/4" and III 3 1/4" done by sectioning middle also? MKIV is different, much slimmer but vertical height is 4". MKIV I had Ian Sammis make for me and should be the same as MKI. What % of volume are MKIII and MKIV and how is it calculated. The whole volume of the amas compared to the total weight of boat? Do you use 1/2 angles for designing front of boat?

You never answered my Question " How do I install the keel trunk now that the main hull halves have been assembled". I believed I talked to Ian and he does it before. Also while looking there is nothing under the mast pivot. " Will the trunk support it. Does the trunk go in the same location as MKI".

Everybody: What shape, area, length, thichness ( %of width ), location of max. thickness ( % aft ). do you use for Keel, rudder, rudder end plate. The Nightmare has the rudder made fom helicopter blades. Keel shape rectangular, area -18.5 sq. in., length-10.8", thickness 15%, max. 35% aft. Rudder same material, area - 11.3, length - 6.6". No rudder end plate yet. These seem to work very well, tacks as fast as a monohull if winds are over 3mph but they don’t look rght. I am going to build a new set with more area but less thickness.

Nightmare weighs 5# - 2oz. ready to sail.

Dear William,
to answer one question after the other! -
The floats of ‘Nightmare’ Mk I and IV - with 4 3/4" height have approx. 300% Volume - 7500cm3 - if the whole boatweigth is still at 2.5kg! -

But if the boatweight is 3.0kg, the float volume is only 250% again! -

Mk III - with 3 1/4" - should be at 230% - 5750cm3! -
Hannu’s ‘Code RED’- (Mk II) - got 3 1/2" height - and is 250% - 6250cm3! -

This is not a question of absolute weights and dimensions - it’s a question of comparisons, proportions and relations! -

Mk IV -the ‘Superslim’ - got 4" height, but is slimmer than the original Nightmare - and got approx. 230% volume - same as Mk III. - Less wetted surface in lightwind conditions, but in a sudden gust the wetted surface of these floats would increase faster than the floats of Mk III. - Which one of these fits best for your personal sailing style and the wind conditions you are sailing in, is a matter of practical testing! -

My own new ‘Nightmare’ Mk VI - which is still uncompleted - will be 4" high at the bow - but with the original width of 8.5cm ( 3 1/4") -and will have approx. 265% floatvolume compared to 2.5kg boatweigth = 6625cm3

Mk IV - ‘Superslim’ - is the fastest lightwind boat - nervous in medium winds or conditions with gusts - tough to sail for strong winds
Mk II - ‘Code RED’- is light to medium wind boat - nervous, but fast in strong winds
Mk III - is a lightwind boat as well, but more forgiving
Mk I and IV are medium to strong wind boats - or most forgiving for beginners
Mk VI - my own boat - MAY have the best OVERALL performance, but it’s not sailing yet -…-

Ernst Zemann

Professional shipwright - boatbuilder/-designer with 25 years of experience and a special interest in multhulls

Ernst: You answered all my questions about the amas except 1/2 angles. Are all main hulls same? Please continue and go on to truck because I want to cut the opening. Anyone else please comment on keels/rudders. I was planing to try something similar to the Pulse on the Nightmare III but keep all the trunks the same so they are interchangeable. They are elliptical with keel area 28.33/11" long, rudder 13.48/7 1/2". I use rudder area 45%-50% of keel. I use .04 x sail area for mono hull. Looks like half .02 for tri. Will have to check out something I saw recently by Lester.

When designing your boats do you use 1/2 angles at the bow both main and amas.

Ernst: Are all my main hulls the same?

I need comments on keel/rudder: shape, size, thickness see above.

Trying to get all the multi discussions back here; Ernst: see my post Aug. 16 Local Pub: Forward screw for the forward crossarm IS THE MAST PIVOT POINT. Please answer my question.

Peter: I do not have the Snapdragon can you send me the shadows. I will send you the Nightmare as soon as I can.

Dear William,
I agree to move the multihull topics back into their original places! -

  1. Half angles - opening angles:
    Yes, of course I use this for design! -
    The ‘Superslim’ - if I recall it right - got 5.5 degrees 1/2 angle = 11 degrees opening angle. -
    For mainhull AND floats exactly the same. The mainhull of the superslim is DIFFERENT to the original Nightmare. I had built a completely new set of plugs! -
    Also the ‘Superslim’ mainhull only got 4.0cm draft, while the original ‘Nightmare’ has 4.5cm. -

The mainhull of the original Nightmare (4" wide and widest point at 45cm from the stern)got an opening angle of only 12 degrees -> 6 degrees 1/2 angle. -
The floats of the original Nightmare have 14 degrees opening angle -> 7 degrees 1/2 angle! -

The mainhull of my last ‘Nightmare Mk VI’ is 5" wide (but this widest point is only at 35cm from the stern). In this way I was able to have the same opening angle as the original Nightmare-floats (14 degrees), but a wider hull overall to have more space for the radiogear, sailwinch AND my thick fingers[:-bouncy]. -

I use rc-helicopter-blades for rudders and centerboards with 15% thickness at 1/3 of the profile. These profiles from the NACA-series are made from CNC-steelmouldings and VERY precise profiles.
Theoretically a 12% profile would be better - less resistance - but handmade profiles can never be as precise as usefull! - Even a tolerance of 1/100 (!!!) at any point of the profile would mess up the waterflow around it and can cause 1 - 5 or even 10% more resistance!!! -
So in ANY case I would prefer helicopter-blades!
And of course carbon is stiffer and better than fibreglass! - A set of female moulds taken from CNC-produced profiles seems to be a good option!-

For the F48:

Rudder size:
In the past I used rudders 6x18cm, 6x 24cm -
and now 4,2cm x 20.0 - 24.0cm! -
The length/width-relation changed from 1:3 over 1:4, 1:5 towards 1:6! -

Centerboard size:
Changed from 6.0 x 24.0 cm and 6.0 x 30.0cm -
to 4.2 x 28.0cm, 30.0cm or even 32.0cm! -
From 1:4 and 1:5 -
to 1:7, 1:7.5 and 1:8! -

But the depth of the water you sail in can definitely cause a restriction here. -

(Just to give you a relation:
My F60 ‘Daydreamer’ got a centerboard of 6.0 x 60.0cm - and a rudder of 6.0 x 30.0cm!) -

Mast pivot point:
At 60cm from the stern! -
If I remember correctly, the ‘Nightmare Mk III’ - NOT the ‘Superslim’ - got TWO optional positions. - One at 60.0cm and one at 65.0cm, but I never used the more forward position! -
This was just a remaining ‘uncertainty’ from the beginning in August 2000! -
Anyway - tilting the mast just TWO degrees more forward or aft will also cause a lateral movement of the center of effort of the rig of around 5.0cm! -
And an exactly vertical mast with a mainsail of 10 % more -
and a foresail with 10% less sailarea - will cause about the same -…-

Outward canted floats:
Hannu’s ‘Code RED’ got them. About 10%. -
It looks good, it’s more complicated to build and I haven’t seen any difference in sailing - or heard of any difference in the sailing performance yet! - I’t more an aesthetic point of view - maybe. -

My humble opinion:
Don’t worry about all that ‘theory’ too much! -
I will give you all necessary informations, to make sure you get the ‘Nightmare Mk III’ and the ‘Superslim’ (which was Mk IV, if I remember correctly? - or was it Mk V?) into the water as fast as possible. -
Sail experience is only gained by sailing - not by thinking! -
I’ve been thinking about that stuff much too much allready - don’t do the same as me -…-
Just go sailing! -

Best wishes, Ernst

Professional shipwright - boatbuilder/-designer with 25 years of experience and a special interest in multhulls

Ernst: Hannu’s ‘Code Red’ " I haven’t seen any difference in sailing- or heard of any difference in the sailing performance yet". As compared to what. It seems that I have all the other Nightmares. Also I have the MKIII crossarm assembled and also the mast and diamonds and shrouds. When turning the mast at 45 degrees the diamonds hit the shrouds. I have used the attachment points that you had already made.

<blockquote id=“quote”><font size=“1” face=“Verdana, Arial, Helvetica” id=“quote”>quote:<hr height=“1” noshade id=“quote”>Originally posted by hoj

Ernst: Hannu’s ‘Code Red’ " I haven’t seen any difference in sailing- or heard of any difference in the sailing performance yet".
<hr height=“1” noshade id=“quote”></blockquote id=“quote”></font id=“quote”>

Hence I have not been sailing the boat :slight_smile: Actually I havent taken it out of the box for a while because of some Rea llife changes, hurries and issues.

The boat is receiving a new rig ( semicomplete ) and the crossbars are bent forward & stiffened for 1 screw attachment now.

Boat weight with very standard radio gear is 2 kgs. I remade the attachment points lighter ( took out the screws ) and changed the wiring to 10 oz spectra fishing line ( very tricky, gets messed up easy and is vulnerable to scrathes when lifting the boat back up after capsize, qualities i dont recommend, but wich i chose to live with ) Also the rig is made more lightweight, as I dont have kids who would mess the boat and i have a good transportations possibilities, so the rig just has to hold together while sailing.

Keeltrunk, I dont know what kind of keeldrunk Ian Sammis is making, but mine is simple carbon tubes and the keel has simple carbon rods wich go into the tubes. The tubes penetrate the whole hull and are attached with epoxy. My opinion is that theres no need for actual trunk, because the keel doesnt have any weight on it. I also have soem extra attachment points for the keel for my rig experiments, so i can adjust the keel attachment point pretty easily.

The boat sailed good “out of the box” so none of these modifications are “a must” I just wanted to experiment a bit and take out the “stock-look” out of the boat and change it to “no compromizes-look”.

  • HJ

“Expertice is gained trough mistakes. However repeating
same mistake is not learning but stupidity.”

What a nice surprise to see your post! -
I thought you might have disappeared completely! -
Please send me an email to:
as I don’t have your current email adress anymore! -
Best wishes, Ernst

Professional shipwright - boatbuilder/-designer with 25 years of experience and a special interest in multhulls