Rear Deck Construction for 8200 "Merlin" type Cowls

[BobGutsell]

Hi Folks

I'm at the stage of my build where I need to build the rear deck to match the cowl. Ideally I want to build the deck so it plugs into the transom then has some sort of retention system under the cowl.

The cowl clips into place using cupboard latches at the rear.

I'm looking for ideas how others have framed the deck and located it.

Could you post photos of your examples please?

Cheers

Bob

 

[P THOMAS]

Build a frame that fits the engine well, probally use some 1/8th ply 1/2 inch strips. If the deck has a curve shape the frame to match. The rear can be held by a couple 6-32 screw thru the transom. i used the left screw for the rudder mount and another the same on the right side of the transom. You can glue in a couple blocks in the front and use screws to hold the front down.

here are some picture of my U10 rear deck.

 

[hugh hargett]

Great looking glasswork PHIL.

Bob, is that the enclosed cockpit oberto hull? If so; can I see the cowl more closely? Who did that for you my friend?

 

[Hydro Junkie]

I have to agree with Phil, though I would make some changes. If the deck has a curve to it, I would make three or four cross frames with legs that go down to the bottom of the boat to get the height correct. My next step would be to make three lengthwise frames, one for each side and one in the middle and glue this framework together. Next, install your retaining system and then add the deck. When the epoxy sets, trim away as much of the excess framing as you feel comfortable with and you're done. If the deck is flat, a simpler framework will due the job just a well

 

[BobGutsell]

Yes Hugh it is indeed the enclosed cockpit 88/89 Oberto. The Glass work is not other that Steve at RC Boatworks. Have alook at his website it shows the cowl as it comes. I've cut the nose cone off and fixed it to the front of the boat along with a couple of bulkheads and alocating pin which took a bit to get right.

 

[hugh hargett]

LOOKS real nice. I love to see not so popular scale hulls. There are some really unique ones out there.

 

[Lennard Cuenco]

bob

i borrowed ideas from roy munoz, doug shepherd, don ferrette, don mock on my rear deck

dropped a oversize piece of foam in tub, used rear deck to shape foam (had deck contour radius' fore/aft and left/right), glassed it/removed foam, drilled 3/16th holes with dowels in transom to hold rear that were sanded flush and can no longer be seen in transom

drilled/tapped aluminum angle for magnets (they make magnets that have 2 countersunk #4 holes mounted to the top of the alum angle, one screw holds the magnet to the alum angle, other screw holds the rear deck down) that hold the cowl down...magnets are covered by rear deck wen mounted

hope this helps

 

[BobGutsell]

Thanks Guys

There's some great stuff there.After seeing Phil and HJ's replies last night I've framed it up as per their instructions.

Yeah Hugh, I liked this one because we don't have unlimiteds in New Zealand just Grand Prix hydros, I thought this one looked like a GP boat on Steroids!

My next question is how do I deal with the rim around the rear of the cowl. Do I cut it into the deck or trim it off and have it blend with the deck profile?

 

[P THOMAS]

I would just add a base to the cowl so it sits on the rear deck. You could add some bulkheads to the cowl also.

 

[BobGutsell]

Thanks Phil

The cowl I have already has a Rim/Flange around the edge of the rear section, should that be flush or upstanding from the deck?

 

[Hydro Junkie]

Here are some pictures of the full sized 8200 cowl that may help you out. Sorry, I couldn't get a shot of the inside with the boat on tilt. Hope they help you

 

[BobGutsell]

Thanks I was looking atn those earlier in your other post. I also had alook at Joe Wiebelhaus' gallery of the same boat (well 83 actually) and he's left the rim stnd proud above the deck which looks like what they did on the real thing.

I think I'm on the right track again now, I'll post some photos of what I've done over the weekend.

Thanks for everybody's help.

 

[BobGutsell]

Well thanks guys, it's trned out great. Here's some piccies of how it went....

 

[Hydro Junkie]

Looks good

 

[Lennard Cuenco]

looks great bob...

i made the rear deck out of glass framed with carbon fiber and 1/16th ply to keep the afterplane as light as possible...at the suggestion of roy munoz...

how much did your rear deck end up weighing? also..my rear deck picked up alot of weight after i sealed/painted....

 

[BobGutsell]

Thanks Lennard, I just weighed it and it's 79 grams, with a coat of sealer on all the undersides.

 

[hugh hargett]

This boat will be so beautful when you get done Bob i remembered you showing it to me when I was asking about the u8900 .I love your boat.

Hugh

 

[BobGutsell]

Wow Thanks Hugh, it doesn't seem far to go now, just finished the canard flaps last night, so this week I build the radio box and confirm where it's going and then it's time for decking. Big thanks for Mike mcknight for contacting me and sending some more photos too. This boat seems to have changed alot during it's two short years in this canopy/merlin configuration.

My only worry is how to get enough ventilation up front to keep fresh air flowing to the engine.

 

[Hydro Junkie]

When you consider that, on the full sized boat, there were openings for the exhaust headers on both sides and the carb air intake through the top, air shouldn't be a problem. If it does prove to be an issue, you can oversize these same openings to a small extent to increase air flow. Having seen both canopied and open cockpit versions of the 8200 run locally, it's never been a problem and the boats have been fast enough to be competitive