With this IOM design I pushed further the idea to reduce the Wet Area.
The LWL is shortened to 900mm.
PDF file attached, better definition then JPEG.
Not excluded to add a chine
Greeting from NZ Claudio,
Have been following your concept with great interest and I have been thinking of trying your short LWL idea which I believe will work well upwind however, I question using the fine ends (Pc 0.557) with this concept with down wind stability in anything but light wind range conditions, thinking it may be problematic unless we can add some reserve buoyancy above the bow sections water-line, what are your thoughts on this ?
Cheers Alan
Hi Alan, very nice to see you back after so long.
I drawn a bow width of 40mm as such to get a tilted freeboard. As said some where else I will try as his, but not excluded to adds a sort of lateral prothesis if needed in the prototype. A sort of profiled foam flared shape magnetically attached. Of course some light iron stripes shall be inserted during hull construction !!!.
Do you remember the 123 tested at 18kt in Frejus ? During gusts, the bow was rising instead to go nose down. This was obtained with the hull balance and CF, and since all my recent designs are following this path.
Anyhow, I’m still away from building start since still under recovery. Probably by the end of the year if all will be OK !
All the best in NZ
Cheers
Claudio
A lot of changes in my mind about a definitive IOM Design.
Most regarding Construction techniques like wood planking !
Also the LWL length is a bit longer to 920mm.
No Chine for the first model called LAZY just in case…
Trimming lines allows to set the best option, small ballasts used at the extremes ends.
File in attachment a Zip file with 100% shadows drawings.
The IOM Lazy construction is started with the Foam method.
The blocs are not yet bonded with White (PVA) Glue.
Sanding permitted after 72 hours.
ClaudioD
To further John’s comments, on my first build of an RG65, I elected to try a simple and quick build - thus electing to go with a JIF65. On this hull (flat panels, hard chine) I purposely shifted the keel back slightly, which raised the bow above the water when not under wind pressure. To my delight, I was able to sail it very strongly in heavy winds. While the bow eventually went down when pressed, I didn’t experience any problems with tripping/nose diving. A DF65 sailing next to me had issues and he resorted to his “B” rig, while I, having only one rig, stayed with the “A” rig.
On the “nARROW”, I have included two brass tubes in the fore deck to handle both a swing rig and a standard rig. I made sure I located the standard rig slightly back which I hope will allow it to handle similar to the JIF65. We will see.
Sorry to drop this post in here, seeing it is an IOM thread, but felt it was a good example of a bow up concept.
Dick
Hi Dick no problems !
Just a step back to my presentation.
The Foam panel choice and setting can be done in different ways. Anyone can develop his method.
Myself, I use the deck plane as a reference.
Doing that, I’m encountering some little problem during sanding at the interface of the two panels.
The area marked with a circle show a sloped body surface.
The bonding contour is rater fragile and foam chipping is very probable due to the different hardness between foam and glued area including white glue. Repair is nevertheless easy with some soft mastic if needed.
To avoid this ‘small problem’ it is possible to set up a different foam assembly.
In the 2nd figure appear a deck plan with stepped blocs. No more interference with sloped surface, but in turn more difficult work when flattening the deck plan during larger and flat surface sanding, including a Deck concave (Stern to Bow) surface if required.
The ideal would be a single Foam panel of 180/200mm thick, it depends on the height size of the model. Larger steps can be previously cut with Hot-wire tool. 3rd figure
To remark that I use the flat deck surface from stern to bow as building reference. My drawings are also based upon a straight line.
Claudio
Here are two photos of the boat I built for my son-in-law (" Dirty Deeds ") and illustrates the amount of bow hull above the water. These photos are in very light winds, plus the transom is only 3.5 cm wide so very little area of drag. As the wind picks up, the hull heels over, until the chine slows the hull from tipping. At that point, the bow begins to drop down towards the water which raises the transom clear of the water and there is a time the bow stem and the stern transom are both clear of the water with the hull at approximately 15 degrees (+/- 5 degrees) of heel.
Hi Dick,
for the benefit of the readers of the n/Arrow design (RG65) I think would be better to post this message there. This tread is supposed to be dedicated to IOM design .
Do you agree ?
Having said that it is comfortable to see the bow up of the " Dirty Deeds ". What is the total weight ?
Thank you
Cheers
Claudio
Just an illustration of a hull with bow up for those wondering “how far up”…
Never did weigh the boat. Son-in-law doesn’t race, so wasn’t too concerned. Will have to take the scales over when I remember them, and check on all up weight.