1976 Starcraft Mariner 21' Layout Changes? (v2)

[alldodge]

Is it you can only reach 4000 rpm then it would be over propped which would lug the motor. If your just cruising at 4000 then this would not be an issue. I hardly ever go above 4000 and can go as high as 6000

 

[jonnyfish]

Is it you can only reach 4000 rpm then it would be over propped which would lug the motor. If your just cruising at 4000 then this would not be an issue. I hardly ever go above 4000 and can go as high as 6000

Oh, I could go above 4000, but that's when it ran rough, so i usually cruised between 4000-4500. So to your point it could have simply had the wrong prop.

However, all that aside, the motor is toast, a rebuild quote at 4-5k on a motor that's worth 1.5k on a good day just doesn't appeal to me. Match that with the gas guzzling nature of an old 2 stroke and a carbed motor and I'm out, haha. Truthfully I'd been contemplating it before the piston ring blew.

 

[redneck joe]

didnt catch this before. why are you lugging the motor. let that thing sing.

I run my little 50 about 4200, gets me to about 20 mph which atm is all i want/need.

 

[roscoe]

ive thought of moving stuff as well, but keeping the center console. The 21 had the console well forward relative to the the 18 per brochure Definitely battery up front and a belly tank.


What hp you running?

Its a 1981 18', with the small 11" splash well, like yours.
Hp ???
Well, that's part of my problem.
Got a lot of weight back there.

A 1986 115 hp inline 6, 315#
and a 1990 15 hp kicker, 75#
and 2 batteries. 80#

 

[roscoe]

 

[jonnyfish]

It was a long delay but the project is finally underway. All decking and old flotation has been stripped out. Running PVC for under deck wire ports and then pouring foam into bags for the under deck. from there i'll start building the main deck flooring and then begin fabricating the splashwell + rear casting deck structure.

If photo uploads work later i'll add them.

 

[redneck joe]

I did the pvc chase as well on my mr180. I would to foam boards over stuff in a bag. If you upload pics to fa ebook or impurities or si ilar you an do old school hot link on pics to here.

Welcome back and good luck.

 

[jonnyfish]

Question on the side ribs. I was initially considering using starboard to replace these. But after reading more I'm not so certain, would it be better to use new marine grade ply, seal it real well, and then paint it the color i'd like (black)?

I definitely don't want to purchase starboard if it's not going to give me the strength i need in structural elements - but curious what you all have done for these.

New photo · Saturday, Aug 9 📸

Tap to view!

photos.app.goo.gl

 

[redneck joe]

The couple three times I've been face with this question I've not convinced myself to use starboard.

 

[jonnyfish]

@redneck joe did you use marine ply? I noticed previously in the build they did not. I'm assuming the only reasonable alternative to that would be something like Western Red Cedar, sealed well (more resistant to rot and solid wood?)

Curious on your thought there.

 

[jonnyfish]

Here are some mock ups of the cast decks and transom fabrication i'm currently targeting. It's gotten easier to visualize this with everything gutted and taken apart. So far I have re-secured the stringers, most of the rivets had let go on them, I then added numerous aluminum cross members to tie into for the flooring, which has also added a great deal of rigidness to the decking structure with the strings and ribs all being tied together with these cross members. Lastly I've run PVC for different wiring lanes as well as the livewell, and leaving some room for drainage after I pour my foam.

From here I'll be doing a leak test to ensure I didn't screw anything up, and then I begin pouring in the foam. After that step I have to bite the bullet and buy a bunch of marine ply. it'll be expensive but I do have access to some better suppliers here rather than going with the menards stuff which I understand commonly has voids and isn't considered high quality.

New photo · Monday, Aug 11 📸

Tap to view!

photos.app.goo.gl

New photo · Monday, Aug 11 📸

Tap to view!

photos.app.goo.gl

New photo · Sunday, Aug 10 📸

Tap to view!

photos.app.goo.gl

 

[redneck joe]

I used mdo grade which is used for outdoor signs. Fours sheets, had about a 40% cut loss on 8 ft sheets. If I could have gotten 10 footers it would have been about 90% utilization. Lots of OTF and one coat primer and three coats rustoleum marine epoxy.

 

[Moserkr]

If thats original wood from starcraft, I wonder if its mahogany. I would save it if possible if thats the case. Otherwise use whatever is cheap and looks good enough for your standards.

Before you do the pour foam, strongly consider gluvit or coat-it inside on every seam and rivet tail below the waterline. It's peace of mind that you are less likely to tear up your floor and foam in the future!! Floor mock up and reinforcements look good!

 

[redneck joe]

Put long 90 degree sweeps on the pvc so they poke up just above the floor line.

 

[jonnyfish]

If thats original wood from starcraft, I wonder if its mahogany. I would save it if possible if thats the case. Otherwise use whatever is cheap and looks good enough for your standards.

Before you do the pour foam, strongly consider gluvit or coat-it inside on every seam and rivet tail below the waterline. It's peace of mind that you are less likely to tear up your floor and foam in the future!! Floor mock up and reinforcements look good!

Great suggestion and I think this is exactly what I'm going to do. I did a leak test last evening, and while i only found a few leaky rivets I definitely want to make this thing as bullet proof and long lasting as possible.

One thing that I didn't love seeing is some leaking coming from the front keel. There's a whole bunch of sealer of some sort on the inside of the boat that potentially gave way in a few small spots. Again the leaks aren't alarming by any stretch, it may come to a cup of water with the boat docked for an entire day - but I'm going to try and address it now with everything exposed.

Regarding that keel area, is it advisable to try and get the old sealant off?

 

[jonnyfish]

After digging around more regarding keel leak repair - and with the minimal leak I'm seeing there - would it be fair to use something like 3M High Strength repair filler on the exterior keel seam? I'm apprehensive to grind off the factor sealant on the inner keel - in the case that I do something wrong there.

If this is reasonable, could I then use this same filler to "shore up" the inner seam that is the splash guard near the water line? Then lastly if I have any left over I could use it for sealing rivets. If I run out I'd then go to gluvit for internal rivet sealing as it's more cost effective - but for the exterior keel I want something a little more "workable" that gets super strong and sets up quicker with less risk of drips etc.

 

[redneck joe]

mine is an 82 and had some goopy crap up there that i was able to spend five minutes prying up then angle grind with a stainless wire wheel. Total time about 20 minutes. I also used 4200 on the outside on the seams. I'm not worries about pretty and it looks odd but it is a good caulk job so doesn't look horrible. I found no leaks but did three coats of gluvit in that area.

 

[redneck joe]

or do the outside sealant and see if that stops it, then make your decision.

 

[jonnyfish]

Providing an update if for no other reason than posterity. While I made some pretty good progress overall I didn't get as far as I was hoping to this year. Sealing the rivets and seams was not something I had built into my timeline, but once it came up it seemed like the right decision. Sealing all rivets and seams below the waterline on a 21' boat is quite the job - it definitely took a while, and I was doing it in 1-2 hour segments after work before I lost my light.

Likewise, I hadn't built in time for properly sealing my deck boards - but as I did the research on floor longevity - skimping on preparation seemed like a dumb choice - with the alternative being replacing the boards in maybe 10ish years which I'm not interested in (I intend to keep this boat for a long time). I double sealed the baseboards with marine epoxy in hopes that it will greatly extend their life and protect them.

That's all the farther I got sadly, I was hoping to have the interior hull primed and painted, the flooring covered with vinyl and installed, and maybe gotten started on building the trussing for the casting decks. But it'll have to wait. The snow will be flying soon here, and having this big beast of a boat in my driveway will make winter miserable. I'm hoping for an early spring so that I can get after it in March, but we'll see what happens.

There's still a very long list of work ahead of me:
- paint interior hull
- vinyl base boarding
- build casting deck trussing
- install fuel tank
- install livewell
- cut/seal/attach casting decking
- cut/seal casting deck hatch doors
- cut/seal/install interior side panels + side panel storage
- build steering console (cut/seal/vinyl) and attach
- run wiring all wiring
- Add Seadek to casting decks and hatch doors
- paint exterior hull
- Add Seadek to gunnels
- clean up and optimize trailer
- probably a dozen more things that will come up

New photo · Monday, Oct 27 📸

Tap to view!

photos.app.goo.gl

 

[redneck joe]

You will be happy in the long run.