Custom/Hybrid Hull Building: USS-ROOSKI

Roo

Roo

it's all good
Site Supporter
Location
Lake Orion, Michigan
Introduction

Before I start, I have to give a big shout out and thanks to Gordon (Flash-FX). Without seeing his bottom hull build thread almost 5 years ago now, I would have never attempted this "madness". He has been my #1 resource and source for inspiration.

A few things:


  • Those who have read Gordon's build thread, this may sound a lot like his.
  • I do NOT do this for a living. I am a 100% amateur when it comes to this type of thing. The approaches/methods I used might not have been the best / efficient, but I learn as I go.
  • I am NOT selling hulls nor getting in the business. This is purely for my benefit.
  • This write-up is for entertainment purposes only.

I attempted this project 3 years ago with a 1996 Yamaha Superjet Hull, but had to give up on it due to unforeseen circumstances. Here is a thread with some pics/details of it for those interested: http://compositescentral.net/showthread.php?t=4463

While I felt like I wasted a LOT of time by not following through, I learned a lot of what to and what not to do, different approaches, how to work with composites, etc. I always wanted to give this project another shot when time permitted... I am glad I waited until now.


I purchased a BRAND NEW aftermarket hull January of 2009 - a RRP Rickter FS-1. One of the first 10 ever produced. It was an all Fiberglass construction and weighed 115 LBS with hood. After 2 seasons of riding, it became clear it was one of the first as it slowly started "deteriorating". I know the quality of them has since gone WAY up, so I can't knock RRP for this. I just happened to have been caught up in all the hype and HAD to have one of the first. I LOVE the way the hull handles. I had 4 different drive trains in it, ranging from 701cc to 1015cc. I mentioned earlier that I am glad I waited - THIS is my favorite all around hull and the one I want to replicate. My two biggest complaints were weight, and quality.


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The bottom half I am going to leave as-is (for now...). The top half, I am going to blend/mold the hood, and make a top cover, as oppose to have a hood (similar that of the Rickter XFS). I may also ditch the adjustable footholds and go back to an XFT/solid state footholds.


Onto the build... enjoy!
 
Roo

Roo

it's all good
Site Supporter
Location
Lake Orion, Michigan
Workshop

I do not have a garage (only a large shed in my backyard). Michigan winters are LONG and COLD. My basement was the best and only solution. I framed in a temporary room with 2"x4"s, and used painters clear plastic sheeting as the walls. I made sure to build this room in a location in my basement that had access to a window for ventilation which is key. I used a combination of box fans which actually worked quite well for ventilation. Occasionally a hint of smell would get into my house but it was not bad and would be gone generally a few hours after whatever I was working on was done. The resins/paints/fumes are NASTY and dangerous. I wore a carbon filter respirator for EVERY step, including sanding. The other most important thing - lighting. I purchased and setup 5 - 4' fluorescent lights (20 bulbs in all, 6500k brightness). PERFECT for seeing any flaw, not casting shadows, etc.


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I also invested money into betters tools - a 60 gallon air compressor (with appropriate regulators, filters, etc), HVLP gun, Gel Coat Dump Gun, DA Sander, Die Grinder, LOTS of clamps, and a few other misc. items.

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Roo

Roo

it's all good
Site Supporter
Location
Lake Orion, Michigan
Hull Plug Bottom Approach

The hull that I am replicating is considered the "Plug" (I will use this term from here on out), from which I will pull the "Mold" off of. First thing is to "true" the Plug, as it had 2 years of abuse, lots of gouges, missing chunks, etc. All hardware had to be removed/cut off, hyrdroturf removed, paint/graphics sanded off... basically a LOT of sanding, bondo, more sanding, bondo, more sanding... you get the picture. In the pump area, all the inserts had to filled in and made smooth as well. NO holes can exist.


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While working on this step, I wasn't sure how to approach the "Flange" for the build, or extensions that would be incorporated/added to the plug at the bondline / side rails (technical term: Joggle Joint). The purpose of this Flange is that it will transfer to the Mold, and when time to use the Mold, will allow room for material run off, and most importantly the Vacuum Bagging process (or maybe Vacuum Infusion?).


There are two problems that had to be addressed - first, the nose of this ski is BLUNT (no join line / joggle joint). Second, the side rails arch up (or down when the Plug is upside down). On a stock RN hull, the bondline / joggle joint runs all the way around the ski and is completely flat (except in the rear).


My first idea was make a cradle, use a piece of masonite, and use foil tape to join it. While it was quick and easy, it seemed a little "hack job"...all well, live and learn.


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I decided to take the same approach Gordon used - use Divinycell (H45 / 3/4" thick / 5 lbs density) for the bulk of it. This stuff is AWESOME. It forms with heat, sands and shapes nicely... but pricey. For fast cutting and shaping, an adjustable (thin) razor works GREAT. The pictures will help quite a bit in explaining this next part. The first step was basically rough out the flange / create the first layer. I used a mixture of Epoxy and Cabosil to "glue" the Divinycell to the hull as it HAD to be a strong bond to the hull and had to be able to support some weight (from materials and me sanding/pressing on it). This took a day to dry completely.


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For the front and rear of the Plug flange, I slowly built it out with strips of the foam (and bondo as glue).


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Once the rough shape was done, the second layer was laid down and "glued" together using bondo (I say Bondo, but I did NOT use the Bondo brand. I used a product called Dynadelite).


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Once the second layer was complete (or near), I had to address the difference in levels between the sides and rear. Two part expanding foam worked great for this.


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Now that the foam part is done , time to seal it all with bondo. I think I laid down 3 layers in all. I SUCK at applying/spreading it, so lots of touch ups and sanding. I was still not sure how I was going to finish the front: Incorporate a Joggle Joint that would also be part of the final part, or keep it flat and have a blunt nose on the final part? Joggle Joint would make the final assembly easier, and possibly stronger, but I like the blunt nose and decided to keep it flat (which means it will need to be glued, then reinforced from the backside).


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Now that all the bodywork and flange is done, time to seal it all up with Duratec Primer. Last time I rolled and brushed this on - HUGE mistake as it left a HUGE texture. It needs to be sanded and polished to a smooth, if not high gloss finish. I used an HVLP gun this time around as I wanted the smoothest finish possible. Duratec calls for 2% MEKP for catalyzation, but I went with 1% to give more working time as I did NOT want the Duratec to gel up inside the gun and ruin in before I could clean it. I used a 1.4MM tip and did NOT thin it, spraying at 40psi. I used I believe around 2.5 quarts on the bottom total, laying it REALLY thick because of the sanding process to follow.


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chad

chad

I pretty much love beer
Site Supporter
Location
Cheney lake Kansas
very nice looking ,very descriptive write up with pictures... just like Gordons build! and I would say your not 100% amateur at this anymore ! Keep up the great work!!
 
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