Mini OB Boat conversion to Mini Jet Boat

Aight guys, I'll keep updating. I hope to get some advice when it's needed, like when I asked about doing a composite transom. I know there are a boat load of pros here. It would be cool to hear everyones thoughts to better my build. This is my first time around so the more help the sicker this boat will turn out. I appreciate your guy's input and help so far. Thanks for following my build!

So here's the new sander at work...




Also sanded the transom...preparing it for fiberglass.




Here you can see we grinded out the transom board behind the stringers. PITA!


VERY NIIIICE!

 

So after we sanded the surfaces I took some acetone and prepped the surfaces.




After that we layed out a large piece of brown packing paper on the transom to trace the shape. Then cut that shape and transferred the template to the chop mat.




We cut 3 layers...2 of those shown here.


Before we layed up glass on the transom we had to fill the voids that were created by grinding out the transom board that was between the outer transom skin and the stringers.

So we measured the MEKP hardener


Poured some resin


Chopped some chop mat up into very small strands, placed them into the resin, and added the hardener.




...and we filled the voids...no pics though.

Then we laid some resin on the transom skin and placed the first layer of chop mat on. Here you can see us wetting the mat after it was in place.






We laid up three layers of 1.5oz chop mat this way, letting it dry to a slight tackiness before starting the following layer.


Garage was at 69º so we wanted to raise the temp so 80º. We placed a space heater and some lamps in place to raise the temp.




And that's is for tonight. More tomorrow guys!

 

Be careful with the MEKP. I wear safety goggles when mixing resin.

 

Are the fumes from it damaging to eyes, or is it just for splash protection?

 

Splash protection. Unlikely, but I don't take any chances with MEKP.

 

Gotcha, I definitely will be careful with the stuff.

We started today by trimming the extra fiberglass off the transom, and cut the pump exit hole in the transom back to shape.

Then we got the ski section placed and cut the back corners off the bottom of the ski section.




Scraped most of the rideplate adhesive away.






Then we feathered the fiberglass edges of the ski section and bottom of the boat so they meet perfectly flush.


Then sanded thru the gel coat to expose the glass to get a great bond.








After we sanded everything down to the fiberglass and got a perfect mesh between the two pieces we set the ski section in place and prepped all surfaces with acetone.








then we put a drill case on the front of the ski section and used a tow strap to ratchet it down just enough to put a light even pressure so it sat flat everywhere. Also in these pics you can see we cut strips of mat to the shape we needed. We cut three layers so we could have them ready to lay just as the previous layer tacked up.




First layer down








Two layers








All three layers finished up.


It was a LOOOOONG day today, but we made a TON of progress. I am hoping to get the interior fiberglassed as well as the gap between the transom and the pump shoe within the next couple days.

 

I will be shaping the bottom of the boat within the next week and I have some questions for the boat experts.

I have searched this forum haven't found the answers I am looking for. There is a lot of information on fairing a hull, but haven't found much info on the process of getting the hull to desired shape...which obviously comes first.

There is info on using a fairing compounds and gelcoats mixed to certain properties to fill minor lows. What I need info on is how to shape the strakes and pad.

Right now I have 3 layers of 1.5oz chop mat that is bonding the two surfaces from the outside, and will later reinforce the inside with 4-5 more layers.

Without taking off much of the glass I laid on the bottom of the boat how can I easily shape the strakes and pad?

Are there any marine products similar to fiberglass reinforced body filler or something that I can build up to blend the strakes out more gradually, and sand more easily than fiberglass?

I've also heard of adding 3M glass bubbles to polyester resin to create a filler that is strong yet sandable. Is this what I should use?

Lastly, is there a good way to sand the flat areas of the strakes to get them smooth and straight enough for fairing compound without hand sanding the fiberglass with a long board?

I know all of the answers are out there, but working my job full time and working on this boat every spare minute I have I have little spare time to spend relaxing, let alone searching on the web. It would be a great to have an experienced boat builders help!

Thanks!

This pic kinda of draws out my plans.


The blue line shows the curvature of the hull in that area that I'd like to keep.
The red arrows point out the areas I'd like to extend the strake out and make them blend gradually.
The green lines show the lines of the strakes and pad that I'd like to keep very straight and sharp.

 

Any help?...plz?

 

I'm not an experienced boat builder, but I suggest that so long as you cover it with enough 'glass, you can use anything to create the basic shape underneath the 'glass. I've used wood, shims from Lowes, green foam from a flower shop, Bondo, probably other stuff I can't recall.

You're doing beautiful work, but one suggestion: see where that resin has run onto the yellow and white gelcoat? It isn't bonding to that gelcoat. When you sand that area, be sure to take it back to where you've exposed "fresh" 'glass. As you sand that line you'll see a tiny edge--that's where a future crack is smiling at you.

Edit: Okay, a second suggestion. Stagger your seams on the mat when you patch the inside.

 

You can get containers of microspheres or microballoons to mix with resin. You can vary the mix to make it thicker where needed. You can make a light easy to sand mix for fairing. You can also get a container of glass fibers to mix in to add strength to build up something.

 

tinhorn- I figured that as long as it was properly sealed so that a small scratch would not reveal the build up material it will work just fine. I appreciate your compliments and I am 100% with you on your suggestions. The resin that got on the gel coat was actually unintentional, haha. We kept the saturated mat within the grinded area. I will definitely remove the resin from the gelcoat. As for the interior glassing, I did exactly as you explained.

We laid 4 layers of mat on the top side of transplant area, staggering small pieces of mat (approx. 4"x4").








The fiberglass work that remains...Stretch fabric between the pump shoe/transom gap, apply resin, and reinforce from the inside. Reinforce motor mounts. Lay 3-4 more layers of fiberglass on transom. Reshape the strakes and pad from the ski section to flow forward and fade out onto the boat bottom.

BPL, what you said is exactly what I've been reading on several other sites and I am confident that those are the two products I will be buying to blend out the strakes and pad gradually. The first step I will use, is blend short strands and microspheres with the polyester resin to get a nice, strong, buildable material and build up that mixture to blend out the strakes in to a dart kind of shape. Then I will use just the microspheres mixed with resin to fill any lows after I sand the darts to shape. Then lay a generous coat of polyester primer.

Thank you both!

 

Just purchased my steering/throttle controls!!!

They may need to be engineered to work perfectly but this will put me way ahead...rather than building something from scratch. It will all be cleaned up, powdercoated/painted, with new red grips and look pretty snazzy after it's installed.

Thanks to Nathan in MI for parting out his WetJet 432 to send me these parts!

The Fighter Jet Steering Wheel


The Throttle Control Trigger


The Steering Column


Throttle Cable (Carb Side)


Steering Cable (Pump Side)


Just wanted to let everyone know a head of time, there will be very little progress over the next 4-5 days. I will be in Vegas! Didn't want ppl thinking I gave up! Haha.

 

OK, I'm supposed to be packing for my Vegas Vaca, but I really wanted to see the pump and engine in place. Here are a couple photos to hold you guys over until the next update mid next week.

 

Got the gap between the pump shoe and the transom glassed last night!

Started by grinding/sanding all of the areas we would be fiberglassing, and also around the motor mounts. We thought we would have time to reinforce the mounts to the floor...but didn't.

We then stretched some white fleece to create the shape, and base that we would build upon. Saturated it from both sides with the Polyester Resin.




Then laid 3 layers of Chop Mat.




After we were done last night after nearly 5 hours we trimmed it up a bit. It will still tacky in some areas and wasn't fully cured to we didn't get to close to the edges.






(in this pic you can see bolts in the motor mount holes. That's because last night we glued the threaded plates in that the motor mounts tap into)






Then this morning I trimmed it up a bit before work, closer to edges.








Tonight we will grind all of the overhang on the outside and shape it a bit. After that we will scuff up the inside of this area with some 40 grit and then fiberglass with at least 3 more layers. We also hope to reinforce the motor mounts tonight.

Don't be afraid to share your thoughts & ideas guys! This is one quiet group.

*Crickets*

 

Nice build! I'm sure you know but you'll need to change the impeller. An impeller off of a XP with a 650 would probably be a good start. You'll want to see about 6750 RPMs. P.s. got to love trond's jetling