Saving Old Seagulls

I saw one entered in the Dartmonth raft race years ago 1992 - just a sealed shell. They had a much lower number than us and so started earlier. They did really well until they got to the wier. It had all but sunk when we passed it.

Charles uk wrote:Can you measure the weight each wheel is carrying with you in it & give us a cross sectional sketch with the wheel locations & the external dimensions, I think without outriggers you might have stability problems.

Yes I think a little forward planning is called for to avoid embarrassment and such, the trim is the hardest part to get right, I'm happy for it to be quite low in the water, which should give me more buoyancy..

fortyplus wrote:

Charles uk wrote:Can you measure the weight each wheel is carrying with you in it & give us a cross sectional sketch with the wheel locations & the external dimensions, I think without outriggers you might have stability problems.

Those Robins had enough stability problems when on three wheels, the tracks look like they might give you quite a bit of weight at the rear corners which will not transfer to stability in the same way low down weight in the middle of the "hull might". In practical term, two outriggers that fold out from the rear inside of the vehicle would be easy to construct and could even be electrically deployed, they could give added flotation and stability. Another thought. that could be better looking, is, being fiberglass it would be reasonably easy to alter the profile of the body in the appropriate areas creating an air filled voids on the exterior surfaces to obtain flotation and stability, I'm picturing something like an exaggerated body kit working like the collar on a rib. There are probably places inside of the body that similar voids could be created for flotation using glass fibre, wheel wells etc. I guess they could be filled with expanding foam to guard against leaking. A cleverly worked front bumper running down the sides and in to a rear bumper could do the job, keeping the bouyancy at the edges would give stability like an inflatable boat. Getting it floating fairly high in the water would overcome the huge drag associated with many amphibious vehicles and help keep your engine out of trouble. You could rough up the basic shapes with thin plywood or even cardbord and then use the fibreglass mat and resin to strengthen them as you mold them to the bodywork. Plenty of filler, some paint and imagination and who knows.

I'm following all your logic there Fourty, but one of the satisfying things about it is that most people think it is a Robin body stuck on a mini digger frame or some such cheat, until they look underneath, and realize it is just all Robin with tracks, so it has to look period original-ish to maintain wonderment and credibility.

There are plenty of voids to foam fill but they unless they are below the water line they may have no buoyancy effect, apart from safety, so perhaps sitting deeper may be an advantage?

The engine is running on neat KSeal and quite near to its demise (I have a spare) and can be considered to be sacrificial for testing purposes, although sealing it is a major hurdle..

fastjedi wrote:I saw one entered in the Dartmonth raft race years ago 1992 - just a sealed shell. They had a much lower number than us and so started earlier. They did really well until they got to the wier. It had all but sunk when we passed it.

It is often the failures that stick in the mind more than the successes, sounds like a good effort though..

Putting the flotation issue to one side for a cogitation period, I have taken the seized Seagull apart for a looksee.

The gearbox was almost full of that white corrosion that comes from ally, and no sign of lube anywhere apart from a dryish coating in the gears that has saved them, but for slight pitting in a couple of teeth, and the pinion bearing is a bit slack.

Water jacket was completely blocked up, piston was seized at top of bore, the drive side crank bearing is seized to shaft, some surface white stuff in crank case but again no sign of any lube anywhere..

Soaked in PlusGas down plughole overnight, then took the flywheel off and that side of crankcase, managed to get the big end off, then got the piston out by brute force, but the crank shaft is still stuck refusing to budge, despite application of every non damaging force applying tool and method I know..

Piston, bore and rings cleaned up very well, despite a layer of corrosion completely filling the clearance space, my method was to put it upside down on the open vise, and really belt it out from the bottom, I think it was wonderfully thoughtful of Seagulls designers to make the exhaust tube exactly the right size and strong enough for this job, I used a bit of wood on top..

Also nice that a bit of 1 1/2" plastic waste pipe is just right to wrap some oxide paper around to clean the bore..

All fixings came undone easily except the tiny big end screws that broke off one ordinary screwdriver and one hardened impact type used with a ratchet and extension!!

It looks like these low tech simple engines are infinitely repairable, I reckon it will be a goodun and run well enough for my usage, thinking of getting a small dinghy to fit the 40+ now...