I'm DESPERATE

[topcat0399]

I have a a poptop.

Its big.

Its heavy.

so. very. heavy.






I know I can use gas strutts, but I don't think they would be the solution I NEED.

I need this thing to go full up and down and stop anywhere it that travel without me
muscling it around, I want to crank something, or screw something, or push a damn button
to be able to adjust it up or down and stop it anywhere.

I am a munchkin so when I'm living in the boat and the weathers nasty or I just need air
I only need to have it up a few inches, and I'm fine. Sometimes I want it half up, or all the way....whatever.

To block the thing open 6 inches requires a full backbreaking lift and a re-set down. It bites. Big.
The thing is great to have but hard hard hard to use.

Like most older mac poptops it rides on 2 sets of aluminum giant U brackets and the top travels through an arc.

When I have mast in travel mode I use it as a beam and can manipulate the top using the main sheet as tackle.
Can't do that when the mast is up, and using the boom as lift point, tackle runs out of travel as the top approaches full up.

I'm thinking a worm gear jack, or a hydraulic ram with a hand pump or something, but everything I find
along those lines are INDUSTRIAL size. Even the small stuff...to heavy for a small plastic boat.
I've looked at lift systems for popup camper tops but it is a lot of hardware that would probably not fit well into a boat.

I'll take any suggestions, I been thinking about how to solve this for years and getting nowhere.



save me

[Jimmyt]

Can you post some pics, or dimensioned sketches, so those that don't know what the top mechanism looks like might be able to give input? Without having the dimensions, linkage layout, etc, it's hard to give meaningful input (unless you own one). Lots of smart folks (wish I was one of them) that might be able to help if they have enough info to work with.

How much does the pop top weigh?

My immediate reaction would be a 12 volt linear actuator ($30 - $300 depending on specs and source).

[topcat0399]

The poptop is approx 60" square (if there be such a thing on a Venture)
And might weigh approx just North of 100 lbs.

I am not bound to the travel being an arc.
I can modify to have the thing go straight up and down
(which I might prefer - haven't decided)

poptop travel.png

IMG_20190604_131258.jpg

poptop IMG_20180526_202310.jpg

[Jimmyt]

Similar pop top with strut assist install.

[topcat0399]

Hes just installing gas struts I believe.
Full up or full down, not what I hope to have but thank you.
Hes pretty darned serial about that poptop safety support.
I can just sling the top from the mast like usual and block it.

Your link to the linear actuator is more in line with the job but best case
would be a light weight manually actuated liner actuator.

Does such a device exist?

Thanks much for the link though.

[Jimmyt]

Yep. Posted the video because it was a similar pop top and showed how he placed the struts. You could replace struts with linear actuators or pneumatic or hydraulic cylinders to automate the lift. My personal preference would be a 12 volt hydraulic power unit with a couple of hydraulic cylinders - if it needs to be installed in the same manner as the struts in the video (one per side). Pneumatics tend to be a bit bouncy for my taste.

The electric actuators can be used, but I'm a little hesitant to use them in pairs. I would be tempted to try to design an approach that would use a single actuator if I went with electric.

Here is a different twist on a pneumatic concept that you may find interesting, also.



Just tossing out some concepts to see if anything starts a collaboration.

[OverEasy]

Hi TopCat0399!

Maybe you might want to consider a pair of scissor Jack (like most cars have nowadays)?
One on each side and possibly a timing belt/sprocket to connect/synchronize them together?
Just an idea….

Another is kind of a two step approach.
For just ‘venting’ where you only want the top up a couple inches on could use a pair of levered progressive cams that you could mount the pivots to the cabin roof. Pulling down or swinging on the handles raises the roof. You could arrange them to go slightly over center to ‘lock’ in place.
Making the handle side longer than the lift side gives you mechanical advantage.
It would at least deal with getting up a bit for ventilation.

After it’s up by a couple of inches you could possibly hook up a ratcheting bi-directional ratchet cable or rope winch to help pull the lid up further but you need to be careful not to be pulling down on the lid, just horizontally.
That would require more thought and looking at the actual hardware/deck/lid more closely.
This would be adding a pair of prop rods that are hinged to the pop top and the other ends with a roller sliding on the cabin deck (probably outside the water lip) in some sort of track to keep it aligned as the rod rollers move fore/aft.
The cables would pull on the roller ends which would push the hinged rod ends up to raise the pop top.
The cables from both rod’s roller ends would run fwd to the reversible ratchet winch with the help of a pair of pulleys.
Crank the winch to tighten the cables to raise the pop top, reverse the winch to lower the pop top, to what height you want.
The pulleys would allow one to locate the winch somewhat out of the way to avoid it being a head knocker .

Just some ideas that don’t require electrics and give you some variability in pop top height.

Hi JimmyT!
> Those air lifters are an interesting idea!
I could enjoy watching a pop top go up and down for an hour or two!
Given adequate space and a pivot bracket on each end of a lifter to take into account the fwd/aft swing of the pop top these would work like a charm!
Not sure on how to get to stable intermediate positions but for up/down they are a great idea.
> Same goes for the gas shocks!
Although having worked with gas shocks for multiple applications/products they can be a bit of a loaded mouse trap even for the cautious.
The pull down handle (or handles) is a good afterthought!
There is also the dexterity aspect of the retainer dogs to hold the pop top from popping!
(Maybe put a light weight crew member on it to launch upon deployment! )
> The linear actuators look nice too!
They could also provide the intermediate positions too!
The synchronization shouldn’t be much of an issue but the where to locate them aspect to avoid being head knockers would require some thought.

Best Regards
Over Easy

[Bobglas]

How about a small fitting attached to front top allowing a block and tackle to attach twixt the top and a spot on the mast (goose eye?) or boom. Drop anchor, go forward hook up the block. Pulls the top forward and up to the desired height, make fast . Voila, simple yet effective.

[OverEasy]

That’s Good Idea BobGlass!

[topcat0399]

How about a small fitting attached to front top allowing a block and tackle to attach twixt the top and a spot on the mast (goose eye?) or boom. Drop anchor, go forward hook up the block. Pulls the top forward and up to the desired height, make fast . Voila, simple yet effective.

It is a good idea and I have considered it before, trouble with that is these old Venture tops
rotate to the rear going up rather than forward like newer Mac popups.

But you have caused me to reconsider the prospect. The top is an awkward lift due to the geometry traveled
and gravity acting on different parts during the lift. Pushing up from below its like a sheet of floppy drywall you are
trying to stick up on the ceiling. Corners flop and sag, and when supporting the corners, the center sags, a clown show.
Even lifting it squarely from above I had to have different length attachments to get a sudden even pull UP
or something sags and binds. I suppose I could reverse everything and have the thing rotate forward going up
since the mast would be a reliable purchase point.

Thanks for the provocation,

[topcat0399]

Hi TopCat0399!

Maybe you might want to consider a pair of scissor Jack (like most cars have nowadays)?
One on each side and possibly a timing belt/sprocket to connect/synchronize them together?
Just an idea….

Another is kind of a two step approach.
For just ‘venting’ where you only want the top up a couple inches on could use a pair of levered progressive cams that you could mount the pivots to the cabin roof. Pulling down or swinging on the handles raises the roof. You could arrange them to go slightly over center to ‘lock’ in place.
Making the handle side longer than the lift side gives you mechanical advantage.
It would at least deal with getting up a bit for ventilation.

After it’s up by a couple of inches you could possibly hook up a ratcheting bi-directional ratchet cable or rope winch to help pull the lid up further but you need to be careful not to be pulling down on the lid, just horizontally.
That would require more thought and looking at the actual hardware/deck/lid more closely.
This would be adding a pair of prop rods that are hinged to the pop top and the other ends with a roller sliding on the cabin deck (probably outside the water lip) in some sort of track to keep it aligned as the rod rollers move fore/aft.
The cables would pull on the roller ends which would push the hinged rod ends up to raise the pop top.
The cables from both rod’s roller ends would run fwd to the reversible ratchet winch with the help of a pair of pulleys.
Crank the winch to tighten the cables to raise the pop top, reverse the winch to lower the pop top, to what height you want.
The pulleys would allow one to locate the winch somewhat out of the way to avoid it being a head knocker .

Just some ideas that don’t require electrics and give you some variability in pop top height.

Hi JimmyT!
> Those air lifters are an interesting idea!
I could enjoy watching a pop top go up and down for an hour or two!
Given adequate space and a pivot bracket on each end of a lifter to take into account the fwd/aft swing of the pop top these would work like a charm!
Not sure on how to get to stable intermediate positions but for up/down they are a great idea.
> Same goes for the gas shocks!
Although having worked with gas shocks for multiple applications/products they can be a bit of a loaded mouse trap even for the cautious.
The pull down handle (or handles) is a good afterthought!
There is also the dexterity aspect of the retainer dogs to hold the pop top from popping!
(Maybe put a light weight crew member on it to launch upon deployment! )
> The linear actuators look nice too!
They could also provide the intermediate positions too!
The synchronization shouldn’t be much of an issue but the where to locate them aspect to avoid being head knockers would require some thought.

Best Regards
Over Easy

I have thought of scissors jack, but what I've look at so far hasn't seem workable.
Not in my pea brain imagination anyway. Maybe I could fashion a scissors arrangement
with tracks out of 1" wide flat stock. hmmmm
Actual car jacks are just too wide, long, massive I think. I need a narrow system I can shoe horn
into the space available.


I have indeed also tried "levering" with rods on the opposite side of the cabin mounted pivot bolts
to cam the thing up. I can get either the front or the rear to go OK but on the initial lift
both front and rear HAVE to move together or the top binds badly and you are going nowhere.

The other things you mention, I have to roll around in my 'ead for a while to
make sure I understand what you are saying. There might be possibility in there...

[topcat0399]

Yep. Posted the video because it was a similar pop top and showed how he placed the struts. You could replace struts with linear actuators or pneumatic or hydraulic cylinders to automate the lift. My personal preference would be a 12 volt hydraulic power unit with a couple of hydraulic cylinders - if it needs to be installed in the same manner as the struts in the video (one per side). Pneumatics tend to be a bit bouncy for my taste.

The electric actuators can be used, but I'm a little hesitant to use them in pairs. I would be tempted to try to design an approach that would use a single actuator if I went with electric.

Here is a different twist on a pneumatic concept that you may find interesting, also.



Just tossing out some concepts to see if anything starts a collaboration.

hmmmm

[Jimmyt]

Pushing up from below its like a sheet of floppy drywall you are
trying to stick up on the ceiling. Corners flop and sag, and when supporting the corners, the center sags, a clown show.
Even lifting it squarely from above I had to have different length attachments to get a sudden even pull UP
or something sags and binds.

This is new information to me. Never been around one, so not familiar with it.

That adds another degree of difficulty to the solution. You could pull it off and glass in an aluminum tube frame to stiffen it up I guess. But, the juice might not be worth the squeeze for you.

The more you tell me, the more I like some sort of air bag lift, combined with some notched or clamping prop rods to allow you to hold it at partially open positions. If the bags have adequate area, it doesn't take much pressure to lift a big weight; they would spread the load over a larger area of your top (lessening the likelihood of ripping it apart compared to a point applied raising force); and if you sew your own lifting bags - might be considerably cheaper to implement. They wouldn't put a knot on your head if you bump into them either.

Years ago, I remember seeing a "safe" vehicle jack that was an air bag with a hose that you put over the exhaust pipe outlet. Just slip the bag under your car and start the motor... Don't think they ever caught on. If they had only included a blower in lieu of using the car engine for a compressor.

My grandkids have an indoor inflatable bounce house (Christmas gift from the Admiral and I). One of their favorite activities with it is; hopping on it while it's deflated and riding it up as it fills. They figured it out on their own. At 2 years old, they are already smarter than me.

Sorry. Here I go rambling...

[NiceAft]

Topcat,

When fully lifted and secured, does it still sag in the middle?

[topcat0399]

Topcat,

When fully lifted and secured, does it still sag in the middle?

It is full up and secured when you let it set/land (CHUNK) forward on the 2 front removable
stanchions.One can choose to install wing nuts on protruding bolts that land thru the
re moveable stanchions. After the first year I never again bothered.

hmm, I would say....Sags in the way any large expanse of a sheet of molded
fiberglass does when the supporting wooden core is likely 90% dry rotted.
Its like a sway back horse, relaxed into its shape over time in 3 planes.

Replacing the core in this thing has been on the list. and on and on and on the ....list.

that darn list

But It can must to a higher priority if it means helping find a workable solution to this sticky wicket.