Boom tube material and fastening

[jelys]

Most boom tubes seems to be made of CF nowadays.

I know the material is lighter and stiffer than aluminium, but as a result of the stiffness it is also more prone to develope cracks. Especially with designs incorporating removable tubes, sponsons and adjustable AOA, there can be many sharp edges/ corners which will further promote cracks.

With adjustable and replaceable booms, what is the best way of securing these to the hull? I have seen used some kind of clamps that in my opinion would be better than drilling a hole through the tube, especially if it is made of CF.

Interesting to get some opinions on this problem.

Regards

Jan Erik

 

[brad nichols]

I drill through the top of the sponson and don't have the brass tube sticking out, easier to finish.

Brad

 

[Hammerhead]

I use electrical tape. $4 a roll Super 33 only. Not the 80 cents a roll cheap stuff. I've used it for riggers up to .90 with no problems.

When you use tape, you don't have to worry about drilling tubes which can cause weak points. It also helps to prevent pulling the outer tubes out of the sponsons when you hit a buoy.

I have been doing it for 25 years, and believe me, I have hit a lot of buoys. I have never pulled an outer tubes.

 

[mercguy]

I use electrical tape. $4 a roll Super 33 only. Not the 80 cents a roll cheap stuff. I've used it for riggers up to .90 with no problems.

When you use tape, you don't have to worry about drilling tubes which can cause weak points. It also helps to prevent pulling the outer tubes out of the sponsons when you hit a buoy.

I have been doing it for 25 years, and believe me, I have hit a lot of buoys. I have never pulled an outer tubes.

Interesting idea. Where do you wrap the tape? Around the boom tube and the tube sticking out of the inside of the sponson?

Bill

 

[Hammerhead]

Bill,

Here is a video of how it's done.

https://youtu.be/UPRL8sZJkuA

Marty

 

[mercguy]

Bill,

Here is a video of how it's done.

https://youtu.be/UPRL8sZJkuA

Marty

That is what I pictured it would be. Thanks for the video, I will try that.

Bill

 

[Hammerhead]

Works the same on any boom material.

 

[gooycheese]

I have taped the outside sponson on like that but never tried a turn fin sponson like that.... would be worried of a failure for sure. I use wheel collars against the tub and on the brass tubes on the sponsons..... on my 45 rigger i put a collar on the outside of the sponson to help hold

View attachment 51665

ohhh yeah been told this is the ugliest boat..... no biggie it runs pretty good.... only if i could drive better...lol

ohhh i never use cf tubes i use cf rods..... i had a chance of trying a epoxy rod a couple weeks ago and turned that down.... seemed really flexy to me.

 

[Hammerhead]

Hey Paul,

On larger boats, I always use tape on the turn find side as well. You are probably right though. I have always had a rod from the tail of the turn find spar to the tub to keep it from pulling away. I use wheel collars on it.

BTW your rigger looks fine.

Marty

 

[Mike Hughes]

Yep, still ugly

.......but I have to say it was moving pretty good in Hobart.

 

[Jim Allen]

I use telescoping tubes with solid rods for mounting sponsons. The woven graphite tubes have 95% unidirectional carbon fiber running longitudinally. The tubes are covered with a light glass scrim & have a high stiffness to weight ratio. I combine these tubes with solid carbon rods made from continuous carbon fibers in a epoxy base. The rods are extremely stiff & lightweight because they use high modulus carbon fiber. The solid carbon rods pass through machined aluminum mounts which have an "O" ring groove in their ID's. The aluminum mounts are grooved on their OD's & are epoxied in place with #406 colloidal silica thickened # 105 resin. The same epoxy mix is used to glue the plugged end carbon tubes into the sponsons. The solid carbon rods are held in place with 1" length carbon tubes epoxied to each side of the hull's aluminum mounts. I slip the tubes mounted in the sponsons over the solid rods & tape them in place with 3M nylon reinforced scotch tape. Tubes glued into the sponsons are mounted in a jig to ensure that all locations are square & identical. An aluminum reinforcement is necessary on the skid fin side. Sometimes in larger hulls the reinforcing plywood piece is replaced with linen based phenolic.

Jim Allen

 

[dwilfong]

I have Jumped my SGX 1.01 boat over 40' in to a fence and tumbled down said fence.

Hence the nick name jumper.............Thanks Joe.................................

NO broken carbon fiber boom tubes.

Have crashed this boat at very high speed many, many times and only one time has a boom broken from a buoy hit.

Ask Jerry it was hauling the mail when it hit it just right.........LOL.........dam slow gas boats in the way................................

Just drill a hole and stick a Teflon washer on it.

Use the solid rod on the inside and it will all be good.

That is unless you just love to tinker........................then all bets are off................................

Not rocket science......................................just a toy boat.......................LOL

 

[John Finch]

I have used the tape method on my SAW rigger and it worked great. I thought I was the only one to do that. I don't know if I would trust tape for ovals though. I have a boat called scrap lumber that I have cut up on the bandsaw many times doing experiments with ground effects. The latest modification before my last two races this year was to make it a rigger with no tubes. Just a foam block sheeted with plywood between the sponsons and hull. No tubes, no adjustments, no worries. Runs great using ground effects to float the boat. No rear sponsons to worry about either.

 

[dwilfong]

I still like the option to put the boat on the table and make adjustment to the sponsons.

Just a small change in the set up will make a big difference on how a rigger will act in racing water.

Also how it will track down the straits and float threw the air with different props.

A small change will make the difference on if it will fall in the holes in the corners and recover or not.

Also how it will pop up in corners and recover in race water.

Now if it is a play boat or a saw boat this is different.

As one racer told me its all just scrap wood at one time or the other.

If you race it will break..................................pick up the pieces and start over......................LOL

The best set up is a easy to fix and easy to replicate at the race.............................................

KISS...................................

 

[Tom Foley]

I still like the option to put the boat on the table and make adjustment to the sponsons.

Just a small change in the set up will make a big difference on how a rigger will act in racing water.

Also how it will track down the straits and float threw the air with different props.

A small change will make the difference on if it will fall in the holes in the corners and recover or not.

Also how it will pop up in corners and recover in race water.

Now if it is a play boat or a saw boat this is different.

As one racer told me its all just scrap wood at one time or the other.

If you race it will break..................................pick up the pieces and start over......................LOL

The best set up is a easy to fix and easy to replicate at the race.............................................

KISS...................................

I still like the option to put the boat on the table and make adjustment to the sponsons.

Just a small change in the set up will make a big difference on how a rigger will act in racing water.

Also how it will track down the straits and float threw the air with different props.

A small change will make the difference on if it will fall in the holes in the corners and recover or not.

Also how it will pop up in corners and recover in race water.

Now if it is a play boat or a saw boat this is different.

As one racer told me its all just scrap wood at one time or the other.

If you race it will break..................................pick up the pieces and start over......................LOL

The best set up is a easy to fix and easy to replicate at the race.............................................

KISS...................................

We'll see how well she holds up in Brandon at the Nitro Winternationals !! come on up to the BBQ November 14 - 15 at the Suwannee no boat required .

 

[dwilfong]

Spent all week putting it back together for testing.......Will be at Brandon if I don't brake it first...........LOL

Might gust show up this time........could use a break.................

 

[Tom Foley]

We'll get you a ride in a fast boat or you can shoot video from my pontoon boat . Massive BBQ and fire both nights going to be sick . Just to stay on topic I use aluminum Boom material and 6- 32 screws for my Hydros except the Eagles .

 

[Jim Allen]

scrap lumber_resized.jpgI have used the tape method on my SAW rigger and it worked great. I thought I was the only one to do that. I don't know if I would trust tape for ovals though. I have a boat called scrap lumber that I have cut up on the bandsaw many times doing experiments with ground effects. The latest modification before my last two races this year was to make it a rigger with no tubes. Just a foam block sheeted with plywood between the sponsons and hull. No tubes, no adjustments, no worries. Runs great using ground effects to float the boat. No rear sponsons to worry about either.

I agree John. It works great for oval boats also & the nylon reinforced tape is almost strong enough by its self to hold up on the skid fin side. It must be wrapped tightly several times! Which method do you think gives less drag, round tubes, square tubes or air foil shaped pieces?

JA

 

[John Finch]

scrap lumber_resized.jpgI have used the tape method on my SAW rigger and it worked great. I thought I was the only one to do that. I don't know if I would trust tape for ovals though. I have a boat called scrap lumber that I have cut up on the bandsaw many times doing experiments with ground effects. The latest modification before my last two races this year was to make it a rigger with no tubes. Just a foam block sheeted with plywood between the sponsons and hull. No tubes, no adjustments, no worries. Runs great using ground effects to float the boat. No rear sponsons to worry about either.

I agree John. It works great for oval boats also & the nylon reinforced tape is almost strong enough by its self to hold up on the skid fin side. It must be wrapped tightly several times! Which method do you think gives less drag, round tubes, square tubes or air foil shaped pieces?

JA

Jim,

I tried the airfoil and the problem was that if the front of the boat hits a wake and lifts, then the airfoil lifts the front of the boat even more and then she is an airplane. I believe for a no lift situation at all angles of attack the round tube is the way to go. On my scrap lumber the boat has a blunt leading edge on the block between the sponsons and hull to help reduce the quick reaction to AOA changes but I had to keep reducing the length of the block between the sponson and hull as the boat would blow off too easily with AOA changes. Eventually I had to add the spoilers to the tops of the sponsons and finally got control of the ride even with big AOA changes. The boat has been to three major races with no blowoffs.

 

[Jim Allen]

John,

That's the same thing I found with adjustable airfoil shaped pieces on the tubes. Even with very negative angles of attack on the airfoils, once the front of the boat became positive enough, the thing was a kite. Throttling down at the first signs of this made the situation worse.