martno1fan

Im sure they will be fine what you say about adding lift till she gets on plane makes sense mate,i know some will disagree but i found strakes do help with stability but hey ask 5 people the same question and you will get 5 different answers on here .Im glad your enjoying the build thats what its all about,im enjoying the hydro build but i still cant wait to get it running if you know what i mean .
Mart

Dreamin Hemi

I have no doubt they do assist with stability of a moving boat, plus I'm adding turn fins plus I added wide and deep strakes to the edges of the hull botton from the front to the back of the transom. Add in 3 inches of rudder hanging bellow the hull, you have your stability!!!!! I just re-read your thread again Mart, lots of great info! I'll surely use that in constructing my plug.

patriktegelberg

It all looks good to me. Nice project and nice of you to share. I believe some stop their strakes short to lose some lift on the stern and get a better angle of attach for the hull and some "boat in the water". You work fast and it can be seen that it is not your first time building stuff. Your boat will be scratch built, partially redesigned and a big achievement.

dwr9

I'm not sure if you need the strakes at all depending on what you're using for power. This hull at the original 48" length has too much lift in the front end even without strakes if you're using a Zenoah or equivalent. Mine has no strakes at all and really wasn't meant to have any. If you're using heavier less powerful engines such as weed wacker motors they may help. It all depends on what you're planning on doing with the hulll and how it's set up. Doug

Dreamin Hemi

Thanks for the input. Whether I need them or not, they're there now on and damn, they look good! Just getting ready to final coat with gel coat. All sanding finally complete. Let's see, 5 coats primer and sand and primer and sand and primer and sand.....the hull plug will be white as I have a gallon of finishing gel coat from West Mariine left on the shelf.

Dreamin Hemi

Patrik, thanks for the compliments. Like I mentioned earlier, I'm a shop class teacher, and absolutely love making things with wood. Usually furniture, so this is just for fun. I'm really coming to like gel coat better than my usual enamel work. Seen here is the completed bottom hull. All imperfections removed prior to final paint. I have applied two medium and one heavy coat of gel coat to this plug. Seems such a shame it's "only" a plug, looks to good! Will let it cure for a few days maybe a little less, and wet sand perfectly smooth and high speed buff/polish. Will start on the upper deck once the gel has fully cured. Notice the flanged lip on the edge. I didn't want a "shoe box" fit with the lid as sometimes they pop loose when bumped (had an Aeromarine boat that happened to). The outward flange is very strong and adds tremendous rigdity to the hull, pretty much elininates buckling. I did intend for this type seam on this hull. Good for me as I tend to be a little rough with my toys

jacob711

wow that looks awesome nice work

dwr9

That looks great. Doug

ByronRC

My Feedback: (2)

Dreamin Hemi, can you explain the complete process on the way you start from wood to a smooth plug to lay up of a mold and part from mold. I've always been interested in that and am wondering if your gonna explain it in your build

Dreamin Hemi

There are several lengthy threads on this site about scratch building. Since threre are so many, I didnt want to steal their thunder and basically repeat pages of already great information. I will be going into more detail once I start wet sanding the plug and begin to lay glass over it for my molds. I have 3 to build for this project; hull, top hull, canopy. Here are a few links that will describe different ways to make a boat from plans to working model. I just choose to go a few steps further!
[link=http://www.rcuniverse.com/forum/m_5452887/anchors_5452887/mpage_1/key_new%252Cmono%252Cbuild/anchor/tm.htm#5452887]Woody Build[/link]
[link=http://www.rcuniverse.com/forum/m_6435388/tm.htm]Woody Build 2[/link]
[link=http://www.rcuniverse.com/forum/m_6080728/tm.htm]Woody Build 3[/link]
[link=http://www.rcuniverse.com/forum/m_5452887/anchors_5452887/mpage_1/key_new%252Cmono%252Cbuild/anchor/tm.htm#5452887]Woody Build 4[/link]

patriktegelberg

How do you apply the gelcoat to get the smooth texture? spray or roller or? it can not be brushed to that result i guess.

Dreamin Hemi

The gel coat was sprayed on with a SLIGHTY thinned mixture using acetone. Only mixed what I needed for each coat. I think 3.5 oz for 1's and 2'nd coats, and I used about 5.5 for the final.

Dreamin Hemi

The "smoothness" besides being sprayed on, is also the result of hours of prep work on the hull itself. Lots of sanding, use of Bondo and finishing glazing putty. Once that was near perfect, several coats of primer were applied and sanded inbetween using glazing putty where needed. Once there were no more flaws, it dried in heat of 130 degrees F for about an hour and cooled. Wiped down with PPG Wax and Grease Remover and applied my layers of gel coat. Not an easy or quick process, but it's the only way to make a perfect finish. With this being a plug, I want it perfect. Flawless plugs equal flawless molds equal flawless glass hulls.

Dreamin Hemi

I'm trying to show the importance of wet sanding here. With the gel coat being ****e, it's very hard to take a picture close up. The first pictures show the "raw" spray up close. Normally gel coat is sprayed directly into a perfectly smooth mold. This stull is thick and requires a special gelcoat spray gun sprayed at about 90 psi. I prefer 95 myself. What this picture shows is orange peel. Sort of like the surface of the fruit, small raised bumps and valleys. Hard to notice from afar, but easily visable up close.
The next picture shows how wet sanding with 400 or 600 grit paper knocks off the peaks and creates a smooth surface. The bubbles you see are from the soap that was added to my quart rinse container, just a few drops of detergent are all that you need to make the sanding block glide over the surface much easier.
The purpose for the water use is to prevent build up under the paper. The water just rolls it away!

Notice the 2'nd picture...the left half of the hull has been partially sanded, while the right side is fully sanded and perfectly smooth, notice the lack of orange peel on the surface.

Dreamin Hemi

Wow, a little compound buffing with a high speed buffer (fine cut) and this is the result of my hard work. A few coats of wax to make the shine even better and this hull plug is ready for molding!

mike the snake

In making the mold, you'll put whatever surface you want on, gelcoat, tooling resin, epoxy or whatever. To make the mold retain it's perfect straightness over time, we put a layer of carbon over the surface, then over that with end-grain balsa, then more glass and another sheet of carbon.

This forms a sandwich out of unstretchable carbon and the end-grain and the mold will never budge. Using epoxy resins will keep the shrinkage down too.

Dreamin Hemi

That will surely be a strong mold. I plan to use Bondo resin soaked pieces of matting. Probably 5 or 6 layers. Never used carbon for a mold, made pleanty of carbon fiber parts with a mold however. For my intensions, that may be overkill. I think that's how my neighbor, Aeromarine Laminates constructs their molds.

ByronRC

My Feedback: (2)

So Dreamin, how many hulls to you plan on pulling from the mold. [sm=wink_smile.gif]
Catch my drift

Dreamin Hemi

Well, right now I've have three in mind. One for myself, one for a buddy...he's just going to borrow the mold, and another guy who is a currently running this same boat as a flat topped woodie, exactly per plan has been stopping by the shop daily to check the progress and getting more excited about it each day. He absolutely loves how HIS handles in the water, and wants a glass hull now with the smooth contours on the sides and nose and molded strakes. So that one I'm selling The hull sold itself as soon as he saw it wet sanded and buffed, before I even showed him the curved top deck idea and hatch. Even if that's the only one ever sold, I at least made all my expenses back, plus have the satisifaction of a well done project....but hey, word travels and who knows!

martno1fan

Stunning work mate i hope the hulls come out as good as the plug once the moulds made ,maybe the plug will still be usable as a boat too after your finnished.Will you be spraying the gelcoat inside your mould or brushing? ive read that brushing it on can yield better results as you dont get and runs or small blemishes when using a brush.As for the strakes creating too much lift for this hull Doug could be right but if they do you can allways use trim tabs to keep her on the water.Great work so far mate ,the only complaint i have is my build wasnt top of that list seeing as i did mine first and its by far the biggest,just kidding
Mart

Dreamin Hemi

LOL....in the back of my mind, I figured you would be the one to make that comment I actually was thinking of that as I searched and posted the links I may have to shuffle a few around just for ya!

Thanks Mart for the compliment as well as you Doug, Jacob...It's been a fun project.

I'm thinking about brushing the gel coat into the mold actually. Spraying would be easy, but I can lay it down thicker using a brush. Any input on this subject would be appreciated! Probably 2 coats brushed in there should take care of it, right?

mike the snake

I sprayed the gelcoat on my first layup. In the corners and edges it got really thick and ran a bit, which was really hard to lay the glass over without forming bubbles.

The second layup I brushed the Gelcoat on. It came out more uniform, but there Were some brush strokes visible. Maybe going over it twice would ensure that doesn't happen.

As long, and flat, and as important is it is to be dead flat, for the $40 it will cost you in carbon and end-grain, IMO it is cheap insurance to make sure the mold stays perfect. Adding the carbon and end-grain will ensure the mold is usable for a long time.

It's such a nice plug, why not make a nice mold too? If the boat totally rocks, you can sell the nice mold for a premium if you like.

From what I've seen on my mold (which is a proffessionally made old working production mold) even if made really thick they can warp and shrink.

As for making the mold itself, whatever you use (gelcoat or resin or tooling resin) use a large syringe and spooge every corner and sharp edge first, then go on with the first thin coat. This will help to keep bubbles from forming.

Bubbles form, and might not be right AT the surface, but when you pull parts those areas can break off and out of the mold easily

This is stuff I've learned from making glider molds, but it totally applies here.

Looks great, good luck!

Dreamin Hemi

Thanks for the advice Mike, I'm making a paste using West Marine Microfibers and will slap that around the strakes and corners to make sure the bubbles stay away. Than I'm laying my 1'st layer of matted glass. Probably will not use carbon, but just curious, where do you find end grain balsa?

mike the snake

CST (composite structures technology I think) or Aerospace composites sell end-grain balsa. Aircraft Spruce might also carry end-grain too.. Tap Plastics sells carbon for around $35 a yard as do both the outfits I just mentioned.

The end-grain gives thickness, forming a sandwich. Just a single layer of carbon above and below the end grain is all it takes to make the whole thing IMMOVABLE forever, I would think one yard would be close to enough. end-grain balsa is cheap.

Think of the carbon and end grain as rebar in concrete.

mike the snake

A mold layup for a wing usually goes;

Tooling resin, (light coat), tooling resin (heavy coat) then a layer of carbon, maybe a layer of glass, then 1/4" end-grain (which bends and flexes and conforms easily to the curves), then a bunch of resin filling in all the voids and spaces in the end-grain, then another layer of carbon, THEN drop on your glass matting or layers of glass.

All this is done in one shot basically, once the tooling resin is kicked off, the rest is just piled on wet.

Another function of the end-grain is it gives depth and thickness without allowing the resin to get thick enough to get hot.

I Hope this helps.