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Old 02-23-2010, 07:07 PM
  #1
SIRI
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Default IOM build

I have a Maniac MKII fiberglass IOM hull, deck and the appendages and post a build log assembling the boat here. Most of the steps I describe can be used assembling other fiber glass boats as well.



I start with the keel box:

I wrap the upper part of the keel with 5 or 6 layers of cling film and grease the surface with petroleum jelly. Then I cut 3 pieces of 125g/sqm fiber glass cloth and one piece of peel ply roughly to size to cover the prepared upper end of the fin with some oversize.
Now I mix some epoxy resin and laminate the 3 layers of fiber glass cloth around the fin layer by layer, cover the laminate with the peel ply and clamp the trailing edge.
I let the resin cure. Now I can remove the laminated keel box from the keel fin and trim it to final shape



I have a keel box now that perfect fits my keel.

The next step will be to prepare the hull and laminate the keel box into it.
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Old 02-25-2010, 06:29 PM
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I mark the center line of the hull at several stations and join the points with masking tape laid in a straight line.
Now I can mark the places for the keel and rudder according to the Maniac MKII's layout plan.


Maniac MKII hull with slot for keel already cut and hole for rudder stock drilled


Now I prepare the keel fin with mold release wax and remove the peel ply from the keel box. Next I prepare the joint surface by sanding it with 80 grit. After this step I slide the keel into the slot in the hull.
Now comes the difficult part.
I adjust the keel with the leading edge square to both beam and water line and the chord in line with the center line and fix it in place.
Now I slide the keel box over the keel inside the hull and laminate it to the hull with some fiber glass cloth and epoxy resin. I cover the laminate with peel ply to get a smooth surface.




keel box laminated into hull and covered with peel ply

When the resin has cured I remove the peel ply


close up of the keel box laminated into the hull - peel ply already removed

Next I will epoxy the rudder stock into the rudder and epoxy the rudder tube into the hull





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Old 02-27-2010, 07:47 PM
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I take the rudder blade, mark it and drill a hole to support the rudder stock into the top. Next I glue the rudder stock into this hole carefully adjusting the alignment to the blade.


Rudder with rudder stock

While the rudder assembly cures I build a support disc for the rudder tube with a diameter of about 20mm and a hole to accommodate the rudder tube from a piece of ply wood


Rudder tube with support disc

After the rudder blade assembly has cured, I apply mold release to the rudder stock. Now I assemble the rudder through the corresponding hole in the hull and assemble the disc and the tube inside. I adjust it to be in line with the keel fin and the water line and epoxy the disc with the brass tube to the hull. I cover with some peel ply to get a smooth surface.



Rudder aligned to keel fin


I remove the peel ply after the epoxy has cured


Rudder tube epoxied into the hull - peel ply removed

Next I epoxy the reinforcements to the deck and cut the hatches
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Old 02-27-2010, 08:35 PM
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Default RE: IOM build

Hey Sirit,
             Keep the photos and descriptions coming.I have had a few questions answered already from your posts.
Richard
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Old 03-01-2010, 07:27 PM
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I cut the reinforcements from 4mm ply wood according to plan and mark the positions on the inside of the deck.


Reinforcement positions marked inside deck molding


Ply wood reinforcements

Now I sand the marked spots to ensure a good adhesion and glue the reinforcement parts in place with epoxy.
Once the resin has cured I carefully mark the positions of the rudder tube, the hatches and other hardware, drill all holes and cut the hatches.


Holes drilled and hatches cut


Next I will match the deck to the hull and install the R/C tray
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Old 03-03-2010, 07:27 PM
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I glue the fairleads for jib sheet and main sheet to the deck according to the boats plans.
I am going to use a pull-pull rudder control and glue two plastic tubes where the control lines exit through deck to the inside of the deck with epoxy.


rudder line tubes glued to the deck

The top of the keel box will be epoxied to the deck under side. I put the deck on the hull and mark the cut on the top of the keel box. I cut careful and test fit. When it fits perfect, I slide the keel fin into the keel box and mark it at top of the keel box. Now I trim the keel fin to match with the keel box.

I cut the servo tray and the pulley support from 4mm ply wood according the templates that came with the boat. Now I paint the wooden parts with a coat of epoxy for waterproofing. I assemble the servo tray and fixate with cyano glue. Now I glue the tray parts together and glue the tray and the pulley support into position with thickened epoxy.


Ply parts cut out


Servo tray assembled


Sail winch and rudder servo test fit

When the resin has cured I install sail winch, rudder servo, pulleys and sheeting according to the plans that came with the boat and test the installation.


Winch and sheeting installed


Next I will glue the deck to the hull

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Old 03-04-2010, 07:54 PM
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I have chosen to glue inwhales to the deck to faciliate snap in and an extended gluing surface inside - inwhales can be wood or PVC foam and can be either glued to the deck or to the hull.
I cut my inwhales from 4mm PVC foam about 5mm wide and glue them to the sanded inside of the deck molding slightly inside the contours with epoxy resin.


Inwhales glued inside deck

Now I carefully match the deck to the hull. At the transom of the sanded hull, the rudder tube and the keel box joints I use a stripe of adhesive foam tape as barrier to prevent the resin from flowing away from the joint.


Soft foam tape as resin barrier

I cover the outside edges of the hull and the deck with masking film for easy removal of resin spills.


Masking tape outside the joint

Now I mix enough thickened epoxy resin to glue the whole hull-deck joint and fill into a small plastic bag. I cut one edge of the bag open and squeeze the resin to the deck half of the joint. I attach the deck to the hull and secure in place with strips of masking tape. After taping the whole joint I insert keel fin and rudder, check the alignment and do corrections if necessary.


Deck glued to hull and secured with tape


Next I will trim the joint and glue the bulb to the keel fin


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Old 03-06-2010, 08:05 PM
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Default RE: IOM build

I remove the appendages after the resin has cured. Now I remove the masking tape strips and carefully trim the seam at the deck-hull joint with sand paper. Then I remove the protective masking tape from deck and hull. I bolt mast step and other rigging hardware in place.




deck - hull joint trimmed - mast step and other rigging hardware installed

Now I slide the keel fin back into the keel box, turn the boat upside down and glue the ballast bulb to the keel after aligning it to the center line and canting up 1 degree to CWL. When the resin has cured I drill a hole through the bulb and keel and insert a retaining pin. I filler and sand the bulb. Last I paint the bulb to match the fin in color.

The boat is ready for rigging now.
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Old 03-07-2010, 06:36 PM
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Default RE: IOM build

Here is a short clip from my Maniac MKII's first launch

[youtube]http://www.youtube.com/watch?v=Gke8aPBRmEY[/youtube]

Have fun
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Old 03-07-2010, 10:00 PM
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Default RE: IOM build

Great build, looks great on the water.
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Old 03-10-2010, 05:38 PM
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Default RE: IOM build


A few observations on the Maniac MkII.

Your keel fin "box" is very flimsy. Most IOMs have cross beam bracing here, plus additional hull strengthening and a Mast Post for rigidity. Your keel fin would flex the fibreglass hull. Where is the Main Sheet Post? Looks like the rudder servo sits where the post should be. Or is the tiny hole between the two servos meant to be for the main sheet? Batteries - you have not used a "pot" with a screw lid to hold batteries and receiver as per 99% of IOM builds. Where do you have the batteries? Are they loose under the front deck with those two huge cutouts. Means removing deck patches every time you sail to remove batteries. You have a stepped mast; so no Mast Ram. All modern IOMs have a 'thru the deck mast' with a Mast Ram. With your deck design this is impossible as the foredeck is too far forward at the cockpit. You have omitted showing any details of your sheeting layout above deck. Is the small hole in the foredeck meant to be the jib fairlead? If so this boat is rigged just like my old MRP 1M Voyager. Not like an IOM. You have your pulleys glued to small pieces of ply below deck. If they foul you have no access. Same with spring at bow. Why did you build an IOM which has no design features of an IOM?

In the video the boat barely heels. Means you were sailing in light winds. Boat stalls when trying to tack. Looks like it wants to nosedive in even these light winds. Most IOMs have a bow depth of 110 - 120 mm. Your boat looks to have far less freeboard. I'd guess from photos the bow is maybe 80mm deep. Suited to sailing on dead flat water.

Please do not "flame" me (again) for making legitimate observations re your boat. You are selling this boat from your web site. Readers should be aware of the design flaws. If they visit RCGroups.com and look at the IOM Discussion thread they can see some 'real' IOMs sailing.

Below are photos of an IOM build showing a normal yacht.

LL
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Old 03-10-2010, 08:32 PM
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Quote:
ORIGINAL: larrykin


A few observations on the Maniac MkII.

Your keel fin ''box'' is very flimsy. Most IOMs have cross beam bracing here, plus additional hull strengthening and a Mast Post for rigidity. Your keel fin would flex the fibreglass hull. Where is the Main Sheet Post? Looks like the rudder servo sits where the post should be. Or is the tiny hole between the two servos meant to be for the main sheet? Batteries - you have not used a ''pot'' with a screw lid to hold batteries and receiver as per 99% of IOM builds. Where do you have the batteries? Are they loose under the front deck with those two huge cutouts. Means removing deck patches every time you sail to remove batteries. You have a stepped mast; so no Mast Ram. All modern IOMs have a 'thru the deck mast' with a Mast Ram. With your deck design this is impossible as the foredeck is too far forward at the cockpit. You have omitted showing any details of your sheeting layout above deck. Is the small hole in the foredeck meant to be the jib fairlead? If so this boat is rigged just like my old MRP 1M Voyager. Not like an IOM. You have your pulleys glued to small pieces of ply below deck. If they foul you have no access. Same with spring at bow. Why did you build an IOM which has no design features of an IOM?

In the video the boat barely heels. Means you were sailing in light winds. Boat stalls when trying to tack. Looks like it wants to nosedive in even these light winds. Most IOMs have a bow depth of 110 - 120 mm. Your boat looks to have far less freeboard. I'd guess from photos the bow is maybe 80mm deep. Suited to sailing on dead flat water.

Please do not ''flame'' me (again) for making legitimate observations re your boat. You are selling this boat from your web site. Readers should be aware of the design flaws. If they visit RCGroups.com and look at the IOM Discussion thread they can see some 'real' IOMs sailing.

Below are photos of an IOM build showing a normal yacht.

LL
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Old 03-19-2010, 01:44 AM
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Quote:
ORIGINAL: larrykin


A few observations on the Maniac MkII.

Your keel fin ''box'' is very flimsy. Most IOMs have cross beam bracing here, plus additional hull strengthening and a Mast Post for rigidity. Your keel fin would flex the fibreglass hull. .........
I must admit I had the same concern.
I actually had to separate the IOM skiff type hull I have (not one of these boats) previously and fix that exact problem ....... as 2.4kg of lead being waived around over 300mm below the hull when combined with a huge amount of sail for the size of the boat places a fair amount of stress on a unbraced hull, and that must be addressed if you want a usable and competitive boat as far as I am concerned.
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Old 03-19-2010, 06:24 PM
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Quote:
ORIGINAL: kiwibob72


Quote:
ORIGINAL: larrykin


A few observations on the Maniac MkII.

Your keel fin ''box'' is very flimsy. Most IOMs have cross beam bracing here, plus additional hull strengthening and a Mast Post for rigidity. Your keel fin would flex the fibreglass hull. .........
I must admit I had the same concern.
I actually had to separate the IOM skiff type hull I have (not one of these boats) previously and fix that exact problem ....... as 2.4kg of lead being waived around over 300mm below the hull when combined with a huge amount of sail for the size of the boat places a fair amount of stress on a unbraced hull, and that must be addressed if you want a usable and competitive boat as far as I am concerned.

Dear Bob,
I understand your concerns, but if you have a close look on the picture where you see a close up of the keel box laminated to the hull you will see that the glass tape reinforces the hull at the joint. I've seen other build logs where the builder just glues the box into the hull with a big blob of plain resin. The upper end of my keel box hull gets laminated to the deck half with the retaining bolt through deck. My deck is stiff enough to support the keel box without the need of a transversal beam.

Cheers
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Old 03-25-2010, 09:11 PM
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Default RE: IOM build

Here's a clip of the maiden voyage of my latest own design - the Siri

[youtube]http://www.youtube.com/watch?v=hfhyb4T_mNc[/youtube]

Have fun
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Old 03-26-2010, 01:06 AM
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In the video clip

Going downwind you did not let your sails out once. Why?

Cross bracing a keel fin. Basic structural engineering teaches you that, as KIWIBOBB wrote, having a bulb weight of 2.4 kgs suspended almost 300mm from the fulcrum gives you a large bending moment. Having a small bolt through the deck will be OK for a short time. Till it cracks. The hull will crack from constant bending forces. Boats sinks........... not good.

All IOMs have a main cockpit bulkhead. And why do all other builders place braces going from the base of the keel fin to the inwhales? To take up load of sidestays and maintain hull integrity.

These observations are easy to implement and I hope will help you and others build better boats.

Larry.
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Old 03-26-2010, 02:21 AM
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Quote:
ORIGINAL: larrykin


In the video clip

Going downwind you did not let your sails out once. Why?

Cross bracing a keel fin. Basic structural engineering teaches you that, as KIWIBOBB wrote, having a bulb weight of 2.4 kgs suspended almost 300mm from the fulcrum gives you a large bending moment. Having a small bolt through the deck will be OK for a short time. Till it cracks. The hull will crack from constant bending forces. Boats sinks........... not good.

All IOMs have a main cockpit bulkhead. And why do all other builders place braces going from the base of the keel fin to the inwhales? To take up load of sidestays and maintain hull integrity.

These observations are easy to implement and I hope will help you and others build better boats.

Larry.

Because the boat did never sail direct downwind in the clip, Larry!
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Old 04-10-2010, 08:18 AM
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Default RE: IOM build

You are quite incorrect in your comments that "all IOM's" have a cockpit bulkhead. Your observations are also incorrect about the bolt through the deck not being adequate to support the fin. A modern, professionally built IOM has no bulkeads and requires minimal, if any, bracing from the base of the fin box to the gunwhales. A bolt through the deck to secure the fin is a normal method of attachement for a properly designed boat.
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Old 04-15-2010, 06:05 AM
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My main point and thought process is that the bolt is only ever there to support the weight of the keel in a vertical load inside the keel box, and thus stop it falling out being the class rules force the keel to be removable.

When a boat heals over, the mast is being loaded one way due to wind force on the sails, while the weight on the keel goes the opposite direction due to the effect gravity has on the large hunk of lead at the bottom on the blade, which can cause the deck and the bottom of the hull around the keel and mast junction to move in opposite directions under load as a result.

A bulk head or internal support addresses these loads allowing for a more solid interface between the keel and mast, which then removes a lot of the stress from the actual hull form stopping this repetitive flexing - and the subsequent failure due to fatigue (as happened in a second hand boat that I purchased that needed repairing as a result). Even the skiff classes I sailed as a kid some 25 years ago had internal bracing around the mast and center board cases, and they had no loads on the center boards other than sideways force that allow a boat to go in a straight line and not just get blow sideways.

If you want to get specific re what long standing and highly regarded professional builders do or don't do on their high end boats, I suggest you do as I did when I built and/or modified my last two boats, and actually talk to some of them for a good amount of time on what is really required in a hull.

As this information, along with how you distribute the load from where the fore-stay meets the front deck are pretty straight forward things that separate well made high end boats that will last for years, from the 'also ran' that tend to pop up from time to time.
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Old 11-24-2010, 03:08 PM
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Interestign thread. I am a 35+ year sailor and have had a few sailboat models. Lately flying turbines and 40% planes though...

This IOM has me interested though!

Could you tell me where I might find information for a good composite hull and rigging?

Thanks and enjoy your time on the water,
Dave
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