1969 IMP "Thunder" 20 ft, Restoration

[Ptr.Torch]

 

[Ptr.Torch]

I. Traded a snowblower for a boat.

Yeah, this thing is 56 years old. Classic 69 modeling. Classic teal green (yuck!). I'm going from a 10 ft aluminum boat and a 6HP outboard to this. I'm taking a huge step, and it's going to be a huge learning curve. So no room for pride and know-it-all-already-ness. I'm going to need ample and copious amounts of good advice.
So why do it? WHY such a large boat? Why is important.
I will be turning 62 this year. And one thing I'm having trouble getting my brain around if this fact that I'm getting old, and I won't be here forever. My time is growing short. Time, for all of us is of limited quantity. I still feel like the 30 or 40 y.o. version of me. I still think like the 30 or 40 y.o. version of me. I want to do great things. I've got huge dreams and huge plans. (Gee, if I could just win the lottery!) The fact is, that time and money limit our choices and bring some reality into our dreams.
My "WORD" for this year, 2025, is -=Realignment=- 2025 is my year to realign myself with goals and dreams that are doable and have a point and purpose. So why a 20 ft boat that's way out of my league?
When I was a youth, a man from our church took us out on his boat. Mr Greenway took a few of us fishing. I can still remember that, if not the boat or what lake we fished. In my youth, dad and I got to go out with some men from a church in Louisiana and fished the Gulf of Mexico. They pulled up close to oil derricks and we hauled in some huge 'Big Red's'. When I was in the service, stationed at Patrick AFB, FL. Fellow AFTAC'er Carl Swenson took me out on his 18'ft open deck boat and we caught some 'dolphin' (fish so named for the porpuse like face they have) All these events are still fresh in my memories.
As I grow older, I find that I just want to build memories like that with my friends and my family, and my grandkids. So a boat. A boat is a tool. It's a tool I hope to employ and enjoy as I build relationship and create memories with people I love and want to be with.

 

[Scott Danforth]

Teal is still a common boat color

 

[Ptr.Torch]

Okay, so here is what I have figured out so far:
(Catching up)

Engine: Listed as a 165HP, in-line 6, and that leads me to a GMC 250 cid.

Drive: Mercerizer MR (Pre-Alpha). Found a crack in the lower half.

Rot: checked the transom and sides. I find none. The floor might be another story. The ring pulls came out and the floor panels stayed in place when I tried to lift them and look underneath.

To date I have charged the battery, and cranked the engine over. It didn't fire. I didn't try priming it yet. That will come after a compression test. The lower obviously needed to be replaced, so I looked around and found one on Ebay. Bought it and I've got it here at the house. The seals are dry, cracked and need to be replaced, so there is more work to be done there. The upper had no oil in it. It appears undamaged. How or where it leaked too, I can't tell, but the case has zero fluid oil, only a residual coating.

So I pulled the upper off and brought it all back to the house. I can rebuild them here in the garage when time permits and parts are available. The label on the upper says it is for a 120-140 HP. I am thinking maybe someone swapped out the case and re-installed the gears for the 165HP ? Is that possible? In any case, how can I know what gears I'm running here. I looked for some numbers or tag to identify them, but found nothing useful.

 

[Scott Danforth]

If the floor is rotten, the transom and stringers are rotten

 

[Ptr.Torch]

I recall reading somewhere that the older fiberglass boats did not use wood. They are all fiberglass. This is a 1969. Could I be so lucky? I've checked everything, and it all looks, sounds solid. No delam, no rot, no separation so far. The floor isn't even spongy or anything.

So I found seal kits for the Drive and for the engine. (Just in case)

But since the weather has been both wet and cold, I've not done anything on the boat itself. I charged up the battery, and I can crank the engine... but I will be doing that compression test. In a week or three. A little bit of life is taking priority. (Kids are buying their first home, and you help family before working on hobbies..)

I'll report again when I've got more to report.

 

[bajaman123]

You didn't say anything about fuel/fuel tank...I assume you drained out any old fuel and have put in new...or at least have the engine hooked up to a small tank with new fuel for testing purposes? That engine is/was a pretty bulletproof design but years of sitting unused (if this is the case with this boat) will always take their toll on fuel and electrical, especially ignition...systems. Changing the oil before fooling around much is a good idea. Take out the spark plugs and mix up some sort of 'break-free' oil (I personally like mixing Marvel Mystery oil with WD40) and inject liberally into the cylinders before cranking with the starter...turn the engine over by hand (pull the coil wire first!) several revolutions after having let the break-free lubricant sit for several hours. Points could be fused together. Just make sure you have spark and fuel before going to great lengths on the engine.
As for transom rot and your question about 'all fiberglass', I don't know of ANY manufacturer in this time period that didn't use wood in the floors, stringers, and transom. You may indeed be lucky on the transom...but pulling the outdrive and gimbal housing will really let you see what the transom is like...at least in that area, which is one of the most likely to have some sort of water damage. Good luck with the project...and yes, teal is a good boat color still...my 2000 Baja has a lot of it.

 

[Chris1956]

Gee, I always liked teal for boats. I had a '67 Winner with about the same color for some time. Just my preference.

I almost painted my speedboat teal, but the prep work necessary to make (a dark color) it look good was too much. I went with white, so the painting prep was manageable.

I mixed blue and green bottom paint to make a nice teal for my boats for some years.

 

[Ptr.Torch]

April 5th, 2025
The weather has finally started cooperating. I have made some significant progress, where first step are concerned. Everyone said to do a compression test before investing too much in this project. I got that done.
[COMPRESSION TEST]
All six cylinders are firing on 120 - 145 psi.
Primed carb with gas and it tried to run.

Fuel line was dry, even after all the cranking for the compression test and it spinning over from priming the carb. (No worries here about pump damage since the outdrive has been removed)
[CLEAN UP]
I started by cleaning out all that fall left behind. Piles of leaves. I removed the two old crusty seats, and replaced them with these two I had on hand. I picked up an electric fuel pump and a block off plate for the mechanical pump. Deleted the busted (inoperative) pump and mounted the electric pump near the fuel filter. The filter is a spin-on like an oil filter. I bought a replacement fuel filter. Wired the pump to the coil.. I looked for another source, but didn't find one. It has to be powered off the key switch, like the coil is. So that works.

[BAD GAS]
The main tank is full. The Aux tank is at 1/2. (if the gauges are reading right) the last use of the boat was 2023 (two years ago) and the gas in the old fuel filter was like water. Any thoughts on A. drain it all start fresh? or is there a way to judge if it can be -treated- and used? Maybe a couple bottles of octane boost and mix 1/2 and 1/2 with new gas??

[FLOORS]
Only two narrow hatches are made of wood. Plywood. They hold, but look a bit scetchy. Everything else is fiberglass! I looked into replacing these with marine grade ply. I've heard about marine grade since I was a teenager. No one in Idaho caries it. CDX is as close as I'll get without making a special order. (?) is Marine grade worth the extra cost? Take into account that the boat is already 56 years old.

 

[Drivewayboater2]

You never mentioned any investigation on transom and stringers. I’d check those before moving forward with any projects.

 

[matt167]

Your electric fuel pump must be wired through an oil pressure switch per USCG regs. The coil will only have 6-9v on it through the resistive wire as well.

 

[Ptr.Torch]

You never mentioned any investigation on transom and stringers. I’d check those before moving forward with any projects.

I've seen plywood in 5 places. All minimal in size or structure. Everything is fiberglass.. even the floors are fiberglass under what remains of that blue carpet. I took soundings for de-lam and found none. the covers over the bilge(?) are plywood. There are two more that serve as lids to two built-in 'buckets that have insulation around them and a drain at the bottom.. so NOT a live fish well, unless that gets a plug. the other two places are part of the engine cover and one up under the transom (inside) which I think is more for mounting and not structural

 

[Ptr.Torch]

Your electric fuel pump must be wired through an oil pressure switch per USCG regs. The coil will only have 6-9v on it through the resistive wire as well.

I saw that option in the instructions. Sorta defeats the point of running an electric pump if you need oil pressure built up BEFORE it will pump the gas. ??Would they have a problem with a Priming circuit?? A push button to run the pump momentarily until the fuel system is fully charged? The way this thing is built, it must have 8 to 10 feet of hose in the system from the tank to the carb. If that goes dry, one would have to crank the engine an awfully long time to fill it all back up just to get it running again.

 

[matt167]

I saw that option in the instructions. Sorta defeats the point of running an electric pump if you need oil pressure built up BEFORE it will pump the gas. ??Would they have a problem with a Priming circuit?? A push button to run the pump momentarily until the fuel system is fully charged? The way this thing is built, it must have 8 to 10 feet of hose in the system from the tank to the carb. If that goes dry, one would have to crank the engine an awfully long time to fill it all back up just to get it running again.

You run a bypass from the starter solenoid. Will run the pump with the key in start position. Let off and it’ll run as long as you have oil pressure