Jetcraft Hobie Jet Fishermn

[RedBarron55]

I just bought a 1995 Hobie Jet fisherman with the 90 HP Sport Jet and I am working to get it running and cleaned up.
Here are a few pictures

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• RedBarron55
• Dec 6, 2017
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• RedBarron55
• Dec 6, 2017

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• RedBarron55
• Dec 6, 2017

20171128_191436

• RedBarron55
• Dec 6, 2017

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• RedBarron55
• Dec 6, 2017

So far I can get it started and idling rev up a little.
I have checked and adjusted the timing and synchronized the carbs.
The starter needed to have the Bendix greased and the solenoid rewired.
I have pulled the carbs for cleaning and found a few drops of water in the #2 carb and when I spilled the contents of the #3 carb I saw a good bit of water in the gasoline on the bench.
The carbs have the new style floats that are nor adjustable and do not have the clearance for the main jets.
See http://forums.iboats.com/forum/engine-repair-and-maintenance/mercury-mariner-outboards/428580-mercury-sportjet-90-bogs-past-4k/page4 post #47.
Does anyone know if these new floats are a problem?
If they do cause a problem at WOT does anyone know where three can be found?

 

[itsdgm]

I love it. That's a pretty cool boat @RedBarron55 Id imagine it's very functional for shallow water fishing too.

Sorry, that I don't have and advice on the carb situation. I'm sure somebody will.

 

[zipper]

Looks like a nice little flats boat. My suggestion is to get new non ethanol fuel and add some SeaFoam to the fuel and run it. I managed to clean out some plugged up high speed jets this past spring on an engine that bogged when I throttled above idle. No problems since.

 

[RedBarron55]

I have cleaned the carbs and found some water in the lower carb and less in the 2nd carb.
I think there was water in the 2nd carb, but since it feeds the enrichment valve it probably was fed there so was less left.
The water I saw in the bottom carb was probably enough to be sucked into the main jet when the throttle was advanced.
I haven't had a chance to run the engine again to see as I need to make an adapter for the cooling water to keep from blowing off the ride plate.
I have been luck (?) since I was using the flush inlet to run the engine (mistake).
I also learned that is you turn up the water pressure you will fill the cylinders and hydraulic the engine.
Hopefully I have been lucky and not damaged the motor.

Also I have decided that this boat is heavy riding lower in the water than it should.
In the rear on both sides there are large square chambers most probably for flotation and they seem to have been glassed in with polyester mat. This mat has separated from the epoxy hull (probably because the mold release was not cleaned completely)
These have listed and the bilge water is under it. If my suspicions are correct the foam within is saturated and needs to be removed.
My plan is to take a vibrating saw and cut that loose "flange" off and clean it up and reglass it with epoxy and cloth as it should have been in the first place.
Before that I plan to cut the top off (square) and pull out and replace the foam. While I am in there I will glass the seams again with cloth and epoxy to make sure it is sealed. Then after refilling glass the top back on.
I hope that the flotation under the floor in front is OK.
Does anyone know how to tell without cutting a hole?
Perhaps I can install an out of sight access hatch under the console.
I would weight the boat and trailer, but there is not a nearby scale and I don;t have the weight of the trailer.
The empty boat should weigh about 875 lbs.

 

[Ben Okopnik]

I hope that the flotation under the floor in front is OK.
Does anyone know how to tell without cutting a hole?

Assuming the flotation is attached under the sole, you can knock on it with a rubber mallet; you'll hear it right off (a dull "thud" is bad news; what you want to hear is a high-pitched "tock" sound.) That's how surveyors test sailboat decks, which due to all the plywood coring that was used back in the 80s and 90s have a huge rot problem.

Also, a removable access hatch (Beckman, among others, makes nice recessed/waterproof ones) would let you reinspect it easily, so I wouldn't be too shy about cutting holes in the floor.

And that's a nice boat, like other folks have said!

 

[RedBarron55]

Thanks for the reply Ben.
I will try the thonk on the floor and hull to see what I can find out.
I am pretty sure the large flotation chambers in the rear have a problem, but they are easy to handle.
These boxes were glassed into the rear with polyester mat and are made of glass / polyester. The mat stuck to the boxes, but not to the hull and the mat and gelcoat has peeled up or flaked off.
I am sure that this is a part of the problem and the reason the boat was sunk at the stern.
When it warms up a little I am going the finish synchronizing the engine carbs and timing and then attack the flotation problem in the rear.
I am going to use my Shearline trailer scale to weigh the boat and trailer to get an idea of the extent of the problem.
The scale is a hydraulic ram with a scale that I can put under a bottle jack and raise each side off the ground and list the tongue to get combined weight.
The boat should weigh 875 empty and the trailer says 600 lbs for a total weight of 1475.
So each side might weigh 750 and the tongue 175 or so.
We shall see

 

[RedBarron55]

I got out and weighed the boat and trailer and got the following numbers:
Right axle 540

Left Axle 550

tongue -175lbs

So right - 545
Left - 550
Tongue - 175
wheels 70
Hubs 14
Total 1354
If the boat weight 875 then the trailer must weigh 479.
Maybe the boat is not waterlogged or my scale is way off.
I tested the scale pretty close by standing on it and it might have been a few lbs light. If my calculations are light maybe 4%. If this correction is correct then the total weight would be 1409 lbs.
The original estimate was 875 boat plus 600 trailer for 1475 lbs so 1409 is not far off the estimate.
It all depends on the weight of the trailer in real life.

 

[swatski]

I got out and weighed the boat and trailer and got the following numbers:
Right axle 540

Left Axle 550

tongue -175lbs

So right - 545
Left - 550
Tongue - 175
wheels 70
Hubs 14
Total 1354
If the boat weight 875 then the trailer must weigh 479.
Maybe the boat is not waterlogged or my scale is way off.
I tested the scale pretty close by standing on it and it might have been a few lbs light. If my calculations are light maybe 4%. If this correction is correct then the total weight would be 1409 lbs.
The original estimate was 875 boat plus 600 trailer for 1475 lbs so 1409 is not far off the estimate.
It all depends on the weight of the trailer in real life.

Your measurements maybe close, which would be wonderful news! Finding a boat like that that is dry is not easy!
However, to really get a total weight you will need to put the whole boat/combo on a scale (a trip to a weighting station may be in order). It is possible to calculate the weight from the measurements you are doing, but it is not trivial. (The tongue weight measured this way is fine though!)
But - when you try to get at the gross weight, the axle is a lever and the axis between the trailer jack and the other jack becomes a fulcrum - the further out from the center you measure the less load you will read (at that point). For example, if you extend that axle with a "cheater" bar far enough, you will be able to lift it with one hand, not because the weight drops but because you will have more leverage.

I do think your maybe pretty close, but it wouldn't hurt to get a more accurate gross weight.

--

 

[RedBarron55]

You are right, but the question is the accuracy of my scales and the problem of getting the boat off the trailer to get a tare weight.
As to the lever arms etc you have a point, but the trailer was on jack stands under the axle and the tongue wheel a plane defined by three points.
I just barely lifted the axle off each jack in turn and the tongue at the same height as static so the lever arms are not an issue here.
I might be able to jack the boat off the trailer when I think about the problem some and at least get a proportional weight. if I can get one weight then if I can take the whole thing to the scale I can calculate pretty closely.
However I think that this gives me a little relief on the boat being waterlogged!!
By the way this included a 6 gallon fuel tank full so about 36 lbs there.
If the scales were to read 10% light the weight would be 1622 lbs - 36 for the gas - 1586 lbs.
It all comes down to finding the actual the weight of the trailer.
I found the weight of the trailer listed as 400 lbs by Advantage Trailer Company, so if that is right then the total weight of 1409 - 400 leaves 1009 for a weight of the boat - 36 lbs for the gas = 973 lbs which would mean an added water weight of about 100 lbs.
So I think investigation of the rear flotation boxes might well be in order.
If the scales are right and the total is 1354 then - 400 = 954 -63 = 918 - 875 = only 43 lbs additional weight.
Can't be so lucky!

 

[swatski]

However I think that this gives me a little relief on the boat being waterlogged!!

I agree - and that is great news!
Do you get any water or wetness in the bilge after you run in the water? If not, and the bilge stays bone dry (and you already said the deck has no soft spots) - you have nothing to worry about, got yourself a winner!

BUT...

If you keep digging, and dig into those flotation boxes and what not, who knows, you may find some wetness...

And then... you will be tempted to keep digging!

And then... the next thing you know... you are rebuilding stringers and transom! Fun!

You may find this:


And will look like this (for few weeks):



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[RedBarron55]

You are right.
At least the Hobie Jet has no wood in it.
The outboard Hobie Power Skiffs have a balsa core transom but the jet does not.
I expect to open one of the rear boxes to have a look.
At the very least the peeling polyester tabbing needs to be cut out and replaced with epoxy.
Everywhere the polyester has been used in this basic epoxy boat (maybe vinlyester?) it is peeling off along with the mat that was used to bond in the polyester/glass boxes in the rear.

 

[swatski]

At least the Hobie Jet has no wood in it.
The outboard Hobie Power Skiffs have a balsa core transom but the jet does not.

I did not know that, that's great - and would explain the light weight!

I doubt the hull construction is epoxy. I'm thinking - no way really. For one, it would had been cost prohibitive, especially back when the boat was built. It would explain those polyester repairs not holding, but that can also happen with polyester over polyester/vinyl. Basically, once fully cured those resins can never develop a chemical bond, and the strength of the (only available) mechanical bond will depend on how well the surface was prepped, and technique used. Not easy to make it last!

If you need to fix those patches that are falling off, the epoxy is the way to go, in theory. But poly is so much easier to work with, at least I think so. And way, way cheaper. And if you have to finish it off with gelcoat, that's poly, too. So, IDK, I would do poly and gelcoat - you can make it look like new. Just a lot of elbow grease!

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[RedBarron55]

Here is a picture of the tabbing that seals the flotation boxes and holds them in.

The polyester has pulled loose from the hull all the way around and I think I am going to cut the tab as above all the way around and then pull the whole thing out if I can. I have to assume that the foam is a block and the box was installed over it.
The reinstall will be a matter of either cutting access holes in the top or just cut the top off as I said.
When I bought the boat there were about a billion, trillion ants living in this space and the area was wet.
I don't see how the foam could not be soaked

 

[RedBarron55]

I cut the top off the box and the foam is intact, but it is wet on the top since it would have to be since the edge has been open for a while.
I can press down with my thumb and feel some moisture in some, but not all places.
My ohm meter reads about 4 meg ohms when pressed into the foam where is is is damp.
I think that perhaps a pair of welding rods pushed all the way down to the bottom will let me track the resistance from the top to the bottom of the foam.
Or is there a good way to cut a core sample or just dig it all out and start over.

 

[RedBarron55]

I took a metal yardstick and used it to slice a square core out of the foam and found the foam in the middle of the box relatively dry, except for the very bottom.
I extended this trial to the inboard side of the box and used my wet or dry vacuum cleaner as a coring scraper to good effect. When I got to the bottom I found that there was standing water and sucked it up and found that the water in the bilge was sucked under the box as I thought.
I don't know how much water the foam has absorbed, but I am going to pull all of it out and seal the inside and the outside of the flotation boxes on both sides and refill with foam.

 

[RedBarron55]

Today it was warm enough to do some fiberglassing and I bonded the flotation boxes to the bottom and sides andthe spot under tha gas tank.
While I was at it I also sealed the bottom of the anchor storage well in the front with fabric and epoxy.
I used epoxy because I had about a gallon of resin (A+B) and the polyester and gel coad did not stick well at all.
I think that exposure to water did that in.
I have fixed two helicoils that were not installed correctly and stuck out from the engine surface and would have kept the exhaust manifold from mating correctly with the block.
I hope that this will fix the problem of getting water in the #3 cylinder.
One thing that might also help is to move the battery under the console (and installing another for the trolling motor too)
and putting the 16 gallon built in gas tank back in service and removing the 6 gallon Attwood.
I think that the fore aft trim needs to have the weight shifted forward to get the draft less and more clearance for the waterline and exhaust elbow.
I will try to post some more pictures later.
By the way, does anyone have experience with moving the battery forward and it's effect on the boat?

 

[Ben Okopnik]

@RedBarron55, sounds like you've done one heck of a lot of work! I have the same kind of "while I'm at it..." attitude, which has kept me working away on my new-to-me boat for the past several weeks. I'm almost to the point of being satisfied with it, though.

By the way, does anyone have experience with moving the battery forward and it's effect on the boat?

Well, the general advice is "keep weight out of the ends to prevent hobby-horsing", which is always a good idea to whatever extent you can manage it. You've got well over a thousand pounds of boat, fuel, dunnage, crew, etc., which sounds like a lot - until you figure that a (say) 50-lb battery at the end of an 8-foot lever (i.e., 8 feet fwd or aft of center) is going to add 400 lbs to your pitching moment - plus whatever it adds to the roll moment by being off-center athwartships. Pretty much all stuff you'll really regret in a bad seaway.

So, moving it toward center in either plane = better; away from center = worse.

 

[RedBarron55]

Here are the pictures of the patching I did to repair the peeled off Polyester and gelcoat.
The peeling let water get into the flotation boxes and under the floor.
I cut the loose fiberglass "flange" off and sanded, cleaned ans tabbed it with fiberglass fabric and epoxy resin.
The bilge and the anchor storage hatch were loose and I could see water running back and forth.
I propped the front of the boat up for days and also used the wet or dry shop vac to pull the water that drained to the rear out and also used it to suck what was trapped under the foam out.
I found that when I cut off the flanges the water ran out better and the foam on the box on the right dried out where it was damp on the bottom.
I "Assumed" that the same thing happened under the floor when no more water could be drawn out from under.
Here are some pictures of the bilge.

And here is a picture of the incorrectly installed helicoil that kept the exhaust manifold from sealing.

You can see that the gasket was not stuck to the block in this area and ion the other side was a similar bad helicoil and no seal.
I ground these down flush with the block and installed the gasket and manifold.
I have not yet tried out the engine since it is cold and threatening to rain and I also didn't want get oil and water back around the fiberglass work area

 

[itsdgm]

I love following your progress. Thanks for posting it @RedBarron55 keep up the good work.

 

[RedBarron55]

Yesterday was somewhat of an off day being damp and cold.
Today may warm up a little and I might just get back into it.
I have ordered two battery hold downs and some battery cable to move the battery to the console and add a trolling motor later.
I also ordered a rectifier / regulator since I don't think that the one in the boat is working.
I am trying a MOSFET unit used on motorcycles and ATVs and is designed to carry more power and perhaps run cooler and last longer.
The one on the boat was probably killed when the previous owner hooked the battery up backwards and the started wouldn't engage because it was running backwards. At least the ignition still works!

This rectifier should work with either two or three ac inputs. Since the Force has only single phase coils for the alternator I will only hook up the two.
This is rated for as much as 50 amps surge so the 16 amps the red coils can output should be easily handled even with the single phase input.
I will report how this works at $15.99 and free shipping!
Fits Suzuki GSXR1000 motorcycles.